Move clusters counters to batch counting

Move clusters_applications_cert_managers to batch counting

ee/changelogs/unreleased/212962-cluster-distinct_by_user-to-move-to-batch-counting-cert-manager.yml

+---
+title: Move Clusters Application CertManager to batch counting
+merge_request: 28771
+author:
+type: performance

ee/lib/ee/gitlab/usage_data.rb

@@ -199,7 +199,7 @@ module EE
         # rubocop:disable CodeReuse/ActiveRecord
         def usage_activity_by_stage_configure(time_period)
           {
-            clusters_applications_cert_managers: ::Clusters::Applications::CertManager.where(time_period).distinct_by_user,
+            clusters_applications_cert_managers: distinct_count(::Clusters::Applications::CertManager.where(time_period).available.joins(:cluster), 'clusters.user_id'),
             clusters_applications_helm: ::Clusters::Applications::Helm.where(time_period).distinct_by_user,
             clusters_applications_ingress: ::Clusters::Applications::Ingress.where(time_period).distinct_by_user,
             clusters_applications_knative: ::Clusters::Applications::Knative.where(time_period).distinct_by_user,