Remove DOMContentLoaded Eventlisteners

Removing DOMContentLoaded Eventlisteners from
index files since the scripts
are embedded using the defer tag.

app/assets/javascripts/pages/groups/details/index.js

 import initGroupDetails from '../shared/group_details';
 
-document.addEventListener('DOMContentLoaded', () => {
-  initGroupDetails('details');
-});
+initGroupDetails('details');

app/assets/javascripts/pages/groups/labels/edit/index.js

 import Labels from 'ee_else_ce/labels';
 
-document.addEventListener('DOMContentLoaded', () => new Labels());
+// eslint-disable-next-line no-new
+new Labels();

app/assets/javascripts/pages/groups/labels/index/index.js

 import initLabels from '~/init_labels';
 
-document.addEventListener('DOMContentLoaded', initLabels);
+initLabels();

app/assets/javascripts/pages/groups/labels/new/index.js

 import Labels from 'ee_else_ce/labels';
 
-document.addEventListener('DOMContentLoaded', () => new Labels());
+// eslint-disable-next-line no-new
+new Labels();

app/assets/javascripts/pages/groups/merge_requests/index.js

@@ -7,15 +7,13 @@ import { FILTERED_SEARCH } from '~/pages/constants';
 
 const ISSUABLE_BULK_UPDATE_PREFIX = 'merge_request_';
 
-document.addEventListener('DOMContentLoaded', () => {
-  addExtraTokensForMergeRequests(IssuableFilteredSearchTokenKeys);
-  issuableInitBulkUpdateSidebar.init(ISSUABLE_BULK_UPDATE_PREFIX);
+addExtraTokensForMergeRequests(IssuableFilteredSearchTokenKeys);
+issuableInitBulkUpdateSidebar.init(ISSUABLE_BULK_UPDATE_PREFIX);
 
-  initFilteredSearch({
+initFilteredSearch({
   page: FILTERED_SEARCH.MERGE_REQUESTS,
   isGroupDecendent: true,
   useDefaultState: true,
   filteredSearchTokenKeys: IssuableFilteredSearchTokenKeys,
-  });
-  projectSelect();
 });
+projectSelect();

ee/app/assets/javascripts/pages/groups/edit/index.js

@@ -3,16 +3,14 @@ import initAccessRestrictionField from 'ee/groups/settings/access_restriction_fi
 import validateRestrictedIpAddress from 'ee/groups/settings/access_restriction_field/validate_ip_address';
 import { __ } from '~/locale';
 
-document.addEventListener('DOMContentLoaded', () => {
-  initAccessRestrictionField('.js-allowed-email-domains', {
+initAccessRestrictionField('.js-allowed-email-domains', {
   placeholder: __('Enter domain'),
   regexErrorMessage: __('The domain you entered is misformatted.'),
   disallowedValueErrorMessage: __('The domain you entered is not allowed.'),
-  });
-  initAccessRestrictionField(
+});
+initAccessRestrictionField(
   '.js-ip-restriction',
   { placeholder: __('Enter IP address range') },
   'ip_restriction_field',
   validateRestrictedIpAddress,
-  );
-});
+);