Remove nested Promise from groups select

app/assets/javascripts/groups_select.js

@@ -4,9 +4,7 @@ import Api from './api';
 import { normalizeHeaders } from './lib/utils/common_utils';
 import { __ } from '~/locale';
 
-export default function groupsSelect() {
-  import(/* webpackChunkName: 'select2' */ 'select2/select2')
-    .then(() => {
+const groupsSelect = () => {
   // Needs to be accessible in rspec
   window.GROUP_SELECT_PER_PAGE = 20;
   $('.ajax-groups-select').each(function setAjaxGroupsSelect2() {
@@ -94,6 +92,9 @@ export default function groupsSelect() {
       dropdown.style.height = `${Math.floor(dropdown.scrollHeight)}px`;
     });
   });
-    })
+};
+
+export default () =>
+  import(/* webpackChunkName: 'select2' */ 'select2/select2')
+    .then(groupsSelect)
     .catch(() => {});
-}