Add isolation2 and parallel-retrieve test matrix entries

Adds two test matrix configurations:
- ic-isolation2 for isolation2 installcheck cases
- ic-parallel-retrieve-cursor for isolation2 parallel retrieve cursor tests

Default settings apply:
- num_primary_mirror_pairs: 3
- enable_cgroups: false
- enable_core_check: true
- pg_settings.optimizer: ""

.github/workflows/build-cloudberry.yml

@@ -265,6 +265,12 @@ jobs:
               {"test":"ic-fixme",
                "make_configs":["src/test/regress:installcheck-fixme"],
                "enable_core_check":false
+              },
+              {"test":"ic-isolation2",
+               "make_configs":["src/test/isolation2:installcheck"]
+              },
+              {"test":"ic-parallel-retrieve-cursor",
+               "make_configs":["src/test/isolation2:installcheck-parallel-retrieve-cursor"]
               }
             ]
           }'