Resolve ""New branch" and "New tag" actions are pointless on an empty repository"

What does this MR do?

Hide new branch and tag links for projects with an empty repo

Before:

After:

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Please see #39988 (closed)

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #39988 (closed)