Fix MetricGroup overwrites

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

@@ -2,21 +2,21 @@ module EE
   module Gitlab
     module Prometheus
       module MetricGroup
-        extend ActiveSupport::Concern
-        extend ::Gitlab::Utils::Override
-
-        prepended do
-          def self.custom_metrics(project)
+        module ClassMethods
+          def custom_metrics(project)
             project.prometheus_metrics.all.group_by(&:group_title).map do |name, metrics|
-              MetricGroup.new(name: name, priority: 0, metrics: metrics.map(&:to_query_metric))
+              ::Gitlab::Prometheus::MetricGroup.new(name: name, priority: 0, metrics: metrics.map(&:to_query_metric))
             end
           end
 
-          override :for_project
-          def self.for_project(project)
+          def for_project(project)
             super + custom_metrics(project)
           end
         end
+
+        def self.prepended(base)
+          base.singleton_class.prepend ClassMethods
+        end
       end
     end
   end