removes n+1 query from tags and branches indexes

What does this MR do?

Fixes N+1 queries for both BranchesController#index and TagsController#index

Relevant Screenshots

Branches

Before

After

Tags

Before

After

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• 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?

#27379 (closed) #27378 (closed) are partially fixed although some work in Gitaly is still being done to improve these pages even more