Move prometheus-alerts-available inside presenter

ee/app/presenters/ee/clusters/cluster_presenter.rb

@@ -16,7 +16,8 @@ module EE
           'settings-path': '',
           'project-path': '',
           'tags-path': '',
-          'alerts-endpoint': alerts_endpoint
+          'alerts-endpoint': alerts_endpoint,
+          'prometheus-alerts-available': prometheus_alerts_available
         }
       end
 
@@ -29,6 +30,10 @@ module EE
       def alerts_endpoint
         '/' if ::Feature.enabled?(:prometheus_computed_alerts)
       end
+
+      def prometheus_alerts_available
+        'true' if ::Feature.enabled?(:prometheus_computed_alerts)
+      end
     end
   end
 end

ee/spec/presenters/ee/clusters/cluster_presenter_spec.rb

@@ -29,7 +29,8 @@ describe Clusters::ClusterPresenter do
           'settings-path': '',
           'project-path': '',
           'tags-path': '',
-          'alerts-endpoint': '/'
+          'alerts-endpoint': '/',
+          'prometheus-alerts-available': 'true'
         )
       end
 
@@ -41,6 +42,10 @@ describe Clusters::ClusterPresenter do
         it 'alerts-endpoint is nil' do
           expect(subject['alerts-endpoint']).to be_nil
         end
+
+        it 'prometheus-alerts-available is nil' do
+          expect(subject['prometheus-alerts-available']).to be_nil
+        end
       end
     end