Resolve "Combine Deploy Keys and Push Rules and Mirror Repository and Protect Branches settings pages"

What does this MR do?

Combines the options in the following way

CE: Protected Branches and Deploy Keys EE: Protected Branches, Deploy Keys, Push Rules and Mirror Repository

Into a single option called Repository

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #26732 (closed)

EE MR

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1167