Merge branch 'jnnkl-dom-content-loaded-header' into 'master'

Remove obsolete DOMContentLoadedEventListener

See merge request gitlab-org/gitlab!52774

app/assets/javascripts/header.js

@@ -106,7 +106,5 @@ export function initNavUserDropdownTracking() {
   }
 }
 
-document.addEventListener('DOMContentLoaded', () => {
-  requestIdleCallback(initStatusTriggers);
-  requestIdleCallback(initNavUserDropdownTracking);
-});
+requestIdleCallback(initStatusTriggers);
+requestIdleCallback(initNavUserDropdownTracking);