Bring back the resgroup memory auditor feature:

- 4354d336
- 8ede074c
- 140d4d2e

Memory auditor was a new feature introduced to allow external components
(e.g. pl/container) managed by resource group.  This feature requires a
new gpdb dir to be created in cgroup memory controller, however on 5X
branch unless the users created this new dir manually then the upgrade
from a previous version would fail.

In this commit we provide backward compatibility by checking the release
version:

- on 6X and master branches the memory auditor feature is always enabled
  so the new gpdb dir is mandatory;
- on 5X branch only if the new gpdb dir is created with proper
  permissions the memory auditor feature could be enabled, when it's
  disabled `CREATE RESOURCE GROUP WITH (memory_auditor='cgroup') will fail
  with guide information on how to enable it;

Binary swap tests are also provided to verify backward compatibility in
future releases.  As cgroup need to be configured to enable resgroup we
split the resgroup binary swap tests into two parts:

- resqueue mode only tests which can be triggered in the
  icw_gporca_centos6 pipeline job after the ICW tests, these parts have
  no requirements on cgroup;
- complete resqueue & resgroup modes tests which can be triggered in the
  mpp_resource_group_centos{6,7} pipeline jobs after the resgroup tests,
  these parts need cgroup to be properly configured;