Move EE differences for `app/assets/javascripts/issuable_form.js`

The file app/assets/javascripts/issuable_form.js has differences between CE and EE.

Diferences

diff --git a/home/yorickpeterse/Projects/gitlab/gdk-ce/gitlab/app/assets/javascripts/issuable_form.js b/home/yorickpeterse/Projects/gitlab/gdk-ee/gitlab/app/assets/javascripts/issuable_form.js
index c81a2230310..70dbb3e33f7 100644
--- a/home/yorickpeterse/Projects/gitlab/gdk-ce/gitlab/app/assets/javascripts/issuable_form.js
+++ b/home/yorickpeterse/Projects/gitlab/gdk-ee/gitlab/app/assets/javascripts/issuable_form.js
@@ -6,6 +6,7 @@ import GfmAutoComplete from './gfm_auto_complete';
 import ZenMode from './zen_mode';
 import AutoWidthDropdownSelect from './issuable/auto_width_dropdown_select';
 import { parsePikadayDate, pikadayToString } from './lib/utils/datetime_utility';
+import groupsSelect from './groups_select';
 
 export default class IssuableForm {
   constructor(form) {
@@ -20,6 +21,7 @@ export default class IssuableForm {
       gl.GfmAutoComplete && gl.GfmAutoComplete.dataSources,
     ).setup();
     this.usersSelect = new UsersSelect();
+    groupsSelect();
     this.zenMode = new ZenMode();
 
     this.titleField = this.form.find('input[name*="[title]"]');

What needs to be done

1. Use ifEE to safeguard the differences