Merge branch 'remove_alerts_service_from_admin_area_service_templates' into 'master'

Exclude project-only services from the admin service templates area

See merge request gitlab-org/gitlab!20938

ee/app/views/projects/services/alerts/_help.html.haml

-- return unless @project.alerts_service_available?
+- return unless @project&.alerts_service_available?
 
 .js-alerts-service-settings{ data: { activated: @service.activated?.to_s,
   form_path: project_service_path(@project, @service.to_param),