Add frontend support for cluster health alerts

Adds a new query text input for metric alerts

app/controllers/projects/clusters_controller.rb

@@ -4,6 +4,10 @@ class Projects::ClustersController < Clusters::ClustersController
   prepend_before_action :project
   before_action :repository
 
+  before_action do
+    push_frontend_feature_flag(:prometheus_computed_alerts)
+  end
+
   layout 'project'
 
   private

app/controllers/projects/environments_controller.rb

@@ -15,6 +15,7 @@ class Projects::EnvironmentsController < Projects::ApplicationController
     push_frontend_feature_flag(:environment_metrics_use_prometheus_endpoint)
     push_frontend_feature_flag(:environment_metrics_show_multiple_dashboards)
     push_frontend_feature_flag(:grafana_dashboard_link)
+    push_frontend_feature_flag(:prometheus_computed_alerts)
   end
 
   def index