Draft: Remove domain-config-source flag

What does this MR do?

Removes domain-config-source flag and related code to that flag only. The default will now be to initialize the GitLab API client or fail to start if it cannot be reached.

It also disables acceptance tests temporarily which need to be refactored.

TODO

• Added the Changelog (e.g. Changelog: feature) trailer to the commits that need to be included in the changelog
• Added unit tests (if required)
• Added acceptance tests (if required)
• Documentation (if required)
• Code review guidelines
• Go Style guidelines

Related to #382 (closed)