Merge branch 'jnnkl-remove-eventlistener-mr-edit' into 'master'

Remove obsolete DOMContentLoadedEventListener

See merge request gitlab-org/gitlab!55049

app/assets/javascripts/pages/projects/merge_requests/edit/index.js

 import initMergeRequest from '~/pages/projects/merge_requests/init_merge_request';
 import initCheckFormState from './check_form_state';
 
-document.addEventListener('DOMContentLoaded', () => {
-  initMergeRequest();
-  initCheckFormState();
-});
+initMergeRequest();
+initCheckFormState();