Small refactor to GeoNodeStatus and remove disabled cop

What does this MR do?

Partly tackles https://gitlab.com/gitlab-org/gitlab-ee/issues/11454.

I'm not sure how to improve further, but this is a mergable step which allows us to re-enable the cop.

To do

• Refactor to make more testable
• Refactor to remove disable of Metrics/AbcSize cop
• Improve test coverage
  • Exercise everything relevant in the context of both primary and secondary
  • Test all public methods

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team