Speed up group milestones show page
What does this MR do?
It adds an index and reduces number of queries done for this page
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
Speeding up things. It should bring down the load time from ~22 to ~6 seconds.
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
- CHANGELOG entry added
API support added
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 you do - rebase it please)
- Squashed related commits together