gpconfig: improve test performance

Change to `gpstop -u` for a quick GUC reload as opposed to a full
restart during tests. This requires us to choose GUCs that can be
reloaded during a SIGHUP (e.g. change gp_resource_group_cpu_limit to
checkpoint_completion_target).
Co-authored-by: NMark Sliva <msliva@pivotal.io>

gpMgmt/test/behave/mgmt_utils/gpconfig.feature

 @gpconfig
 Feature: gpconfig integration tests
 
-    # Below, we use 2 change (-c) operations to prove that we have changed a file,
-    # because any existing postgresql.conf file could already have the first value in it a priori
-    # NOTE: since we are restarting the database with the given paramaters, do not change parameters
-    #   that will cause the database to not restart given your machine setup.
+    # Below, we use 2 change (-c) operations to prove that we have changed a
+    # file, because any existing postgresql.conf file could already have the
+    # first value in it a priori
+    #
+    # NOTE: since we are SIGHUPing the database after each change (full restarts
+    # would be too slow), you must choose parameters with a sighup or weaker
+    # context.
 
     @concourse_cluster
     @demo_cluster
     Scenario Outline: run each gpconfig command for guc type: <type>
-      Given the user runs "gpstop -ar"
+      Given the user runs "gpstop -u"
         And gpstop should return a return code of 0
         And the gpconfig context is setup
         And the user runs "gpconfig -c <guc> -v <seed_value>"
         And gpconfig should return a return code of 0
         # ensure <guc> is set to <seed_value> for the tests below
-        And the user runs "gpstop -ar"
+        And the user runs "gpstop -u"
         And gpstop should return a return code of 0
 
        # set same value on master and segments
@@ -48,7 +51,7 @@ Feature: gpconfig integration tests
         And gpconfig should print "value: <seed_value> | file: <file_value_master>" escaped to stdout
         And gpconfig should print "value: <seed_value> | file: <file_value>" escaped to stdout
 
-       When the user runs "gpstop -ar"
+       When the user runs "gpstop -u"
        Then gpstop should return a return code of 0
 
       # FIXME: a file string value of 'my_value' (quotes in file) has a live value of my_value (no quotes) and
@@ -65,26 +68,26 @@ Feature: gpconfig integration tests
 
     # test for each type documented for gpconfig
     Examples:
-        | guc                         | type     | seed_value | value    | file_value | live_value | value_master_only | file_value_master_only | value_master | file_value_master | live_value_master |
-        | log_connections             |  bool    | off        | on       | on         | on         | off               | off                    | off          | off               | off               |
-        | gp_resgroup_memory_policy   |  enum    | eager_free | auto     | auto       | auto       | eager_free        | eager_free             | eager_free   | eager_free        | eager_free        |
-        | vacuum_cost_limit           |  integer | 300        | 400      | 400        | 400        | 555               | 555                    | 500          | 500               | 500               |
-        | gp_resource_group_cpu_limit |  real    | 0.4        | 0.5      | 0.5        | 0.5        | 0.33              | 0.33                   | 0.7          | 0.7               | 0.7               |
-        | application_name            |  string  | xxxxxx     | bodhi    | 'bodhi'    | bodhi      | lucy              | 'lucy'                 | bengie       | 'bengie'          | bengie            |
-        | application_name            |  string  | yyyyyy     | 'bod hi' | 'bod hi'   | bod hi     | 'lu cy'           | 'lu cy'                | 'ben gie'    | 'ben gie'         | ben gie           |
-        | application_name            |  string  | zzzzzz     | ''       | ''         |            | ''                | ''                     | ''           | ''                |                   |
-        | application_name            |  string  | boo        | "'\''"   | '\\'''     | \'         | "'\''"            | '\\'''                 | "'\''"       | '\\'''            | \'                |
+        | guc                          | type     | seed_value | value    | file_value | live_value | value_master_only | file_value_master_only | value_master | file_value_master | live_value_master |
+        | log_connections              |  bool    | off        | on       | on         | on         | off               | off                    | off          | off               | off               |
+        | gp_resgroup_memory_policy    |  enum    | eager_free | auto     | auto       | auto       | eager_free        | eager_free             | eager_free   | eager_free        | eager_free        |
+        | vacuum_cost_limit            |  integer | 300        | 400      | 400        | 400        | 555               | 555                    | 500          | 500               | 500               |
+        | checkpoint_completion_target |  real    | 0.4        | 0.5      | 0.5        | 0.5        | 0.33              | 0.33                   | 0.7          | 0.7               | 0.7               |
+        | application_name             |  string  | xxxxxx     | bodhi    | 'bodhi'    | bodhi      | lucy              | 'lucy'                 | bengie       | 'bengie'          | bengie            |
+        | application_name             |  string  | yyyyyy     | 'bod hi' | 'bod hi'   | bod hi     | 'lu cy'           | 'lu cy'                | 'ben gie'    | 'ben gie'         | ben gie           |
+        | application_name             |  string  | zzzzzz     | ''       | ''         |            | ''                | ''                     | ''           | ''                |                   |
+        | application_name             |  string  | boo        | "'\''"   | '\\'''     | \'         | "'\''"            | '\\'''                 | "'\''"       | '\\'''            | \'                |
 
     @concourse_cluster
     @demo_cluster
     Scenario Outline: write directly to postgresql.conf file: <type>
-      Given the user runs "gpstop -ar"
+      Given the user runs "gpstop -u"
         And gpstop should return a return code of 0
         And the gpconfig context is setup
         # we do this to make sure all segment files contain this <guc>, both in file and live
         And the user runs "gpconfig -c <guc> -v <seed_value>"
         And gpconfig should return a return code of 0
-        And the user runs "gpstop -ar"
+        And the user runs "gpstop -u"
         And gpstop should return a return code of 0
 
        When the user writes "<guc>" as "<value>" to the master config file
@@ -95,7 +98,7 @@ Feature: gpconfig integration tests
        Then gpconfig should return a return code of 0
         And gpconfig should print "Master  value: <file_value>" escaped to stdout
 
-       When the user runs "gpstop -ar"
+       When the user runs "gpstop -u"
        Then gpstop should return a return code of 0
 
        When the user runs "gpconfig -s <guc>"
@@ -104,19 +107,19 @@ Feature: gpconfig integration tests
 
     # NOTE: <value> is directly entered into postgresql.conf
     Examples:
-        | guc                         | type     | seed_value | value    | file_value | live_value |
-        | log_connections             |  bool    | off        | on       | on         | on         |
-        | gp_resgroup_memory_policy   |  enum    | eager_free | auto     | auto       | auto       |
-        | vacuum_cost_limit           |  integer | 300        | 400      | 400        | 400        |
-        | gp_resource_group_cpu_limit |  real    | 0.4        | 0.5      | 0.5        | 0.5        |
-        | application_name            |  string  | xxxxxx     | bodhi    | bodhi      | bodhi      |
-        | application_name            |  string  | xxxxxx     | 'bod hi' | 'bod hi'   | bod hi     |
-        | application_name            |  string  | xxxxxx     | ''       | ''         |            |
+        | guc                          | type     | seed_value | value    | file_value | live_value |
+        | log_connections              |  bool    | off        | on       | on         | on         |
+        | gp_resgroup_memory_policy    |  enum    | eager_free | auto     | auto       | auto       |
+        | vacuum_cost_limit            |  integer | 300        | 400      | 400        | 400        |
+        | checkpoint_completion_target |  real    | 0.4        | 0.5      | 0.5        | 0.5        |
+        | application_name             |  string  | xxxxxx     | bodhi    | bodhi      | bodhi      |
+        | application_name             |  string  | xxxxxx     | 'bod hi' | 'bod hi'   | bod hi     |
+        | application_name             |  string  | xxxxxx     | ''       | ''         |            |
 
     @concourse_cluster
     @demo_cluster
     Scenario Outline: gpconfig basic removal for type: <type>
-      Given the user runs "gpstop -ar"
+      Given the user runs "gpstop -u"
         And gpstop should return a return code of 0
         And the gpconfig context is setup
         And the user runs "gpconfig -c <guc> -v <value>"
@@ -133,11 +136,11 @@ Feature: gpconfig integration tests
         And verify that the file "postgresql.conf" in each segment data directory has "some" line starting with "#<guc>="
 
     Examples:
-        | guc                         | type     | value      |
-        | log_connections             |  bool    | off        |
-        | gp_resgroup_memory_policy   |  enum    | eager_free |
-        | vacuum_cost_limit           |  integer | 300        |
-        | gp_resource_group_cpu_limit |  real    | 0.4        |
-        | application_name            |  string  | bengie     |
-        | application_name            |  string  | 'ben gie'  |
-        | application_name            |  string  | ''         |
+        | guc                          | type     | value      |
+        | log_connections              |  bool    | off        |
+        | gp_resgroup_memory_policy    |  enum    | eager_free |
+        | vacuum_cost_limit            |  integer | 300        |
+        | checkpoint_completion_target |  real    | 0.4        |
+        | application_name             |  string  | bengie     |
+        | application_name             |  string  | 'ben gie'  |
+        | application_name             |  string  | ''         |