Don't instrument `app/services/concerns`

config/initializers/8_metrics.rb

@@ -22,7 +22,11 @@ def instrument_classes(instrumentation)
   paths_to_instrument = {
     %w(app finders)                => %w(app finders),
     %w(app mailers emails)         => %w(app mailers),
-    %w(app services **)           => %w(app services),
+    # Don't instrument `app/services/concerns`
+    # It contains modules that are included in the services.
+    # The services themselves are instrumented so the methods from the modules
+    # are included.
+    %w(app services [^concerns]**) => %w(app services),
     %w(lib gitlab conflicts)       => ['lib'],
     %w(lib gitlab diff)            => ['lib'],
     %w(lib gitlab email message)   => ['lib'],