Merge branch 'instrument-repository-class' into 'master'

Instrument the Repository class

## What does this MR do?

This MR instruments the Repository class.

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

No.

## Why was this MR needed?

This class wasn't instrumented.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5621

CHANGELOG

@@ -6,6 +6,7 @@ v 8.11.0 (unreleased)
   - Remove magic comments (`# encoding: UTF-8`) from Ruby files. !5456 (winniehell)
   - Add support for relative links starting with ./ or / to RelativeLinkFilter (winniehell)
   - Fix CI status icon link underline (ClemMakesApps)
+  - The Repository class is now instrumented
   - Cache the commit author in RequestStore to avoid extra lookups in PostReceive
   - Fix of 'Commits being passed to custom hooks are already reachable when using the UI'
   - Add support for using RequestStore within Sidekiq tasks via SIDEKIQ_REQUEST_STORE env variable

config/initializers/metrics.rb

@@ -144,6 +144,7 @@ if Gitlab::Metrics.enabled?
     end
 
     config.instrument_methods(Rinku)
+    config.instrument_instance_methods(Repository)
   end
 
   GC::Profiler.enable