Instrument the Repository class

Since this isn't an ActiveRecord::Base descendant it wasn't
instrumented.

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