Fix some cfg test case naming conflicts
Fix some cfg test case naming conflicts

As pointed out by Vish, there are duplicates of:

  OverridesTestCase::test_default_override
  OverridesTestCase::test_override
  SadPathTestCase::test_conf_file_not_found

Also, rename the ConfigFileOptsTestCase so it is obvious they
don't clash with the tests by the same name in CliOptsTestCase.

Change-Id: I1d650d05d32501623cfed8f0b6399858d101ae02

JioCloud/oslo.config,citrix-openstack/build-oslo.config,tianshan/oslo.config,shad7/oslo.config,citrix-openstack-build/oslo.config,metacloud/oslo.config,magic0704/oslo.config,varunarya10/oslo.config