Add controller#action metrics on Gitaly
This MR add metrics, exposed using Prometheus, for Gitaly calls made per controller#action.
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
Edited by Zeger-Jan van de Weg