add some test results into .gitignore (#16254)

add some resource group test results into .gitignore

src/test/isolation2/.gitignore

@@ -13,6 +13,10 @@ sql/workfile_mgr_test.sql
 expected/workfile_mgr_test.out
 expected/idle_gang_cleaner.out
 sql/idle_gang_cleaner.sql
+expected/resgroup/resgroup_io_limit.out
+sql/resgroup/resgroup_io_limit.sql
+expected/resgroup/resgroup_views.out
+sql/resgroup/resgroup_views.sql
 
 -- ignore generated pg_basebackup tests
 /sql/pg_basebackup*.sql