Merge branch 'jnnkl-remove-eventlistener-admin-services' into 'master'

Remove obsolete DOMContentLoadedEventListener

See merge request gitlab-org/gitlab!56535

app/assets/javascripts/pages/admin/services/index/index.js

 import PersistentUserCallout from '~/persistent_user_callout';
 
-document.addEventListener('DOMContentLoaded', () => {
-  const callout = document.querySelector('.js-service-templates-deprecated');
-  PersistentUserCallout.factory(callout);
-});
+const callout = document.querySelector('.js-service-templates-deprecated');
+PersistentUserCallout.factory(callout);