Merge branch 'jnnkl-remove-eventlistener-new-milestone' into 'master'

Remove obsolete DOMContentLoadedEventListener

See merge request gitlab-org/gitlab!54928

app/assets/javascripts/pages/projects/milestones/new/index.js

 import initForm from '../../../../shared/milestones/form';
 
-document.addEventListener('DOMContentLoaded', () => initForm());
+initForm();