Drop few secs of ICW by running some serial tests in parallel.

No reason was specified for running those tests serially, tried and seem to run
fine in parallel. Also, dropped few drop tables from gpdtm_plpgsql test.

src/test/regress/expected/gpdtm_plpgsql.out

@@ -3,16 +3,6 @@
 -- interesting issues). 
 --
 -- Create some tables with some data
-drop table if exists tabcd;
-NOTICE:  table "tabcd" does not exist, skipping
-drop table if exists tabcd_orig;
-NOTICE:  table "tabcd_orig" does not exist, skipping
-drop table if exists t1234;
-NOTICE:  table "t1234" does not exist, skipping
-drop table if exists t1234_orig;
-NOTICE:  table "t1234_orig" does not exist, skipping
-drop table if exists t3456;
-NOTICE:  table "t3456" does not exist, skipping
 create table tabcd (c1 text) distributed randomly;
 insert into tabcd values ('a'), ('b'), ('c'), ('d');
 create table t1234 (c1 integer) distributed randomly;
@@ -249,12 +239,6 @@ select a.c1 from t1234 a, t3456 b where a.c1 = b.c1 order by b.c1;
   4
 (4 rows)
 
-drop table if exists dtm_plpg_foo;
-NOTICE:  table "dtm_plpg_foo" does not exist, skipping
-drop table if exists dtm_plpg_bar;
-NOTICE:  table "dtm_plpg_bar" does not exist, skipping
-drop table if exists dtm_plpg_baz;
-NOTICE:  table "dtm_plpg_baz" does not exist, skipping
 CREATE OR REPLACE FUNCTION foo_func() RETURNS void AS '
 BEGIN
 update dtm_plpg_foo set a = a + 3;
@@ -981,8 +965,6 @@ exception
 END;
 $$
 LANGUAGE plpgsql SECURITY DEFINER;
-drop table if exists source_table;
-NOTICE:  table "source_table" does not exist, skipping
 CREATE TABLE source_table
 (
 id int,
@@ -994,8 +976,6 @@ insert into source_table select generate_series(1,10), '2015-01-06'::date;
 insert into source_table values (11, '0000-00-00');
 insert into source_table select generate_series(12,21), '2015-01-06'::date;
 CREATE SEQUENCE test_seq START 1;
-drop table if exists dest_table;
-NOTICE:  table "dest_table" does not exist, skipping
 CREATE TABLE dest_table
 (
 id int,
@@ -1010,7 +990,3 @@ select count(1) from dest_table;
     21
 (1 row)
 
-drop table dest_table;
-drop sequence test_seq;
-drop table source_table;
-drop FUNCTION date_converter(input_date character varying);

src/test/regress/greenplum_schedule

@@ -17,8 +17,7 @@
 
 test: variadic_parameters default_parameters function_extensions
 
-test: leastsquares
-test: opr_sanity_gp decode_expr bitmapscan bitmapscan_ao case_gp limit_gp notin percentile naivebayes join_gp union_gp gpcopy gp_create_table
+test: leastsquares opr_sanity_gp decode_expr bitmapscan bitmapscan_ao case_gp limit_gp notin percentile naivebayes join_gp union_gp gpcopy gp_create_table
 test: filter gpctas gpdist matrix toast sublink table_functions olap_setup complex opclass_ddl information_schema guc_env_var
 test: bitmap_index gp_dump_query_oids analyze
 test: indexjoin as_alias regex_gp gpparams with_clause transient_types gp_rules
@@ -74,11 +73,10 @@ test: vacuum_gp
 # ERROR:  parameter "gp_interconnect_type" cannot be set after connection start
 
 ignore: gp_portal_error
-test: external_table column_compression eagerfree mapred gpdtm_plpgsql alter_table_aocs alter_distribution_policy ic aoco_privileges
+test: external_table column_compression eagerfree mapred gpdtm_plpgsql alter_table_aocs alter_distribution_policy ic aoco_privileges aocs
 test: partition_indexing 
 test: alter_table_ao ao_create_alter_valid_table subtransaction_limit oid_consistency udf_exception_blocks
 ignore: icudp_full
-test: aocs
 
 test: resource_queue
 # gp_toolkit performs a vacuum and checks that it truncated the relation. That
@@ -153,11 +151,7 @@ test: uao_ddl/alter_ao_table_owner_row uao_ddl/alter_ao_table_setstorage_row uao
 test: uao_catalog_tables uaocs_catalog_tables uao_ddl/alter_ao_table_setstorage_column uao_ddl/alter_ao_table_col_ddl_row uao_ddl/compresstype_row uao_ddl/alter_ao_table_col_ddl_column uao_ddl/alter_ao_part_tables_splitpartition_row uao_ddl/alter_ao_part_tables_splitpartition_column uao_ddl/create_ao_tables_row uao_ddl/create_ao_table_500cols_row uao_ddl/create_ao_tables_column uao_ddl/alter_ao_part_exch_row
 test: uao_ddl/alter_ao_part_exch_column uao_ddl/alter_ao_part_tables_row uao_ddl/create_ao_table_500cols_column uao_ddl/alter_ao_part_tables_column
 
-test: uao_ddl/alter_drop_allcol_row uao_ddl/alter_drop_allcol_column uao_ddl/alter_rollback_row uao_ddl/alter_rollback_column uao_ddl/uao_allalter_row uao_ddl/uao_allalter_column
-
-test: uao_col/alter_ao_table_oid_column
-
-test: uao_row/alter_ao_table_oid_row
+test: uao_ddl/alter_drop_allcol_row uao_ddl/alter_drop_allcol_column uao_ddl/alter_rollback_row uao_ddl/alter_rollback_column uao_ddl/uao_allalter_row uao_ddl/uao_allalter_column uao_col/alter_ao_table_oid_column uao_row/alter_ao_table_oid_row
 
 # Test psql \du output
 test: psql_gpdb_du

src/test/regress/sql/gpdtm_plpgsql.sql

@@ -3,12 +3,6 @@
 -- interesting issues). 
 --
 -- Create some tables with some data
-drop table if exists tabcd;
-drop table if exists tabcd_orig;
-drop table if exists t1234;
-drop table if exists t1234_orig;
-drop table if exists t3456;
-
 create table tabcd (c1 text) distributed randomly;
 insert into tabcd values ('a'), ('b'), ('c'), ('d');
 
@@ -142,11 +136,6 @@ ABORT;
 
 select a.c1 from t1234 a, t3456 b where a.c1 = b.c1 order by b.c1;
 
-
-drop table if exists dtm_plpg_foo;
-drop table if exists dtm_plpg_bar;
-drop table if exists dtm_plpg_baz;
-
 CREATE OR REPLACE FUNCTION foo_func() RETURNS void AS '
 BEGIN
 update dtm_plpg_foo set a = a + 3;
@@ -339,7 +328,6 @@ END;
 $$
 LANGUAGE plpgsql SECURITY DEFINER;
 
-drop table if exists source_table;
 CREATE TABLE source_table
 (
 id int,
@@ -352,7 +340,6 @@ insert into source_table select generate_series(12,21), '2015-01-06'::date;
 
 CREATE SEQUENCE test_seq START 1;
 
-drop table if exists dest_table;
 CREATE TABLE dest_table
 (
 id int,
@@ -362,7 +349,3 @@ created timestamp with time zone
 insert into dest_table select nextval('test_seq'::regclass), date_converter(created) from source_table;
 select count(1) from dest_table;
 
-drop table dest_table;
-drop sequence test_seq;
-drop table source_table;
-drop FUNCTION date_converter(input_date character varying);