Resolve new EE specific differences in app/

What does this MR do?

This resolves all new/missed EE specific differences in the app/ directory.

This fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/13334

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