Improve EE::MetricGroup

ee/lib/ee/gitlab/prometheus/metric_group.rb

@@ -2,7 +2,11 @@ module EE
   module Gitlab
     module Prometheus
       module MetricGroup
-        module ClassMethods
+        extend ActiveSupport::Concern
+
+        class_methods do
+          extend ::Gitlab::Utils::Override
+
           def custom_metrics(project)
             project.prometheus_metrics.all.group_by(&:group_title).map do |name, metrics|
               ::Gitlab::Prometheus::MetricGroup.new(
@@ -10,14 +14,11 @@ module EE
             end
           end
 
+          override :for_project
           def for_project(project)
             super + custom_metrics(project)
           end
         end
-
-        def self.prepended(base)
-          base.singleton_class.prepend ClassMethods
-        end
       end
     end
   end