Update .gitignore files

To have a clean `git status` output.

src/test/regress/.gitignore

@@ -9,7 +9,15 @@
 # Configure-generated files
 /GPTest.pm
 
+twophase_pqexecparams
+
 data/wet_csv?.tbl
 data/wet_text?.tbl
 data/wet_syntax?.tbl
 data/wet_execute.tbl
+
+regression.diffs
+regression.out
+
+stdin
+stdout

src/test/regress/expected/.gitignore

@@ -38,3 +38,5 @@ trigger_sets_oid.out
 query_info_hook_test.out
 gp_tablespace.out
 partition_ddl.out
+autovacuum-template0.out
+rpt_tpch.out

src/test/regress/sql/.gitignore

+# autogenerated sql files from input dir source files
 /constraints.sql
 /copy.sql
 /create_function_1.sql
@@ -41,3 +42,5 @@ trigger_sets_oid.sql
 query_info_hook_test.sql
 gp_tablespace.sql
 partition_ddl.sql
+autovacuum-template0.sql
+rpt_tpch.sql