Remove old UI (#15414)

* Remove source code for old UI
* Rename ui-next to ui
* Remove license scan for javascript dependencies

awx/main/conf.py

@@ -843,16 +843,6 @@ register(
     hidden=True,
 )
 
-register(
-    'UI_NEXT',
-    field_class=fields.BooleanField,
-    default=False,
-    label=_('Enable Preview of New User Interface'),
-    help_text=_('Enable preview of new user interface.'),
-    category=_('System'),
-    category_slug='system',
-    hidden=True,
-)
 
 register(
     'SUBSCRIPTION_USAGE_MODEL',