refactor: Only display Preview Language Setting (dark_lang) in LMS (#38510)

Co-Authored-By: Kyle D McCormick <kyle@axim.org>

Author: salman2013

cms/urls.py

@@ -7,6 +7,7 @@
 from django.conf.urls.static import static
 from django.contrib import admin
 from django.contrib.admin import autodiscover as django_autodiscover
+from django.shortcuts import redirect
 from django.urls import include, path, re_path
 from django.utils.translation import gettext_lazy as _
 from django.views.generic import RedirectView
@@ -86,7 +87,7 @@
          ),
 
     # Darklang View to change the preview language (or dark language)
-    path('update_lang/', include('openedx.core.djangoapps.dark_lang.urls', namespace='dark_lang')),
+    path('update_lang/', lambda request: redirect(f'{settings.LMS_ROOT_URL}/update_lang/')),
 
     # For redirecting to help pages.
     path('help_token/', include('help_tokens.urls')),

openedx/core/djangoapps/dark_lang/tests.py

@@ -18,7 +18,7 @@
     with_site_configuration,
     with_site_configuration_context,
 )
-from openedx.core.djangolib.testing.utils import CacheIsolationTestCase
+from openedx.core.djangolib.testing.utils import CacheIsolationTestCase, skip_unless_lms
 
 UNSET = object()
 
@@ -259,6 +259,7 @@ def _post_clear_preview_lang(self):
         """
         return self.client.post('/update_lang/', {'action': 'reset_preview_language'})
 
+    @skip_unless_lms
     def test_preview_lang_with_released_language(self):
         # Preview lang should always override selection
         self._post_set_preview_lang('rel')
@@ -272,6 +273,7 @@ def test_preview_lang_with_released_language(self):
         self.client.get('/home')
         self.assert_cookie_lang_equals('rel')
 
+    @skip_unless_lms
     def test_preview_lang_with_dark_language(self):
         self._post_set_preview_lang('unrel')
         self.client.get('/home')
@@ -290,6 +292,7 @@ def test_empty_preview_language(self):
         self.client.get('/home')
         self.assert_cookie_lang_equals('rel')
 
+    @skip_unless_lms
     def test_clear_lang(self):
         # Clear a language when no language was set
         self._post_clear_preview_lang()
@@ -335,6 +338,7 @@ def test_accept_chinese_language_codes(self):
             self.process_middleware_request(accept='zh-Hans;q=1.0, zh-Hant-TW;q=0.5, zh-HK;q=0.3')
         )
 
+    @skip_unless_lms
     def test_language_cookie_is_set(self):
         site_lang = settings.LANGUAGE_CODE
         url = '/dashboard'
@@ -370,6 +374,7 @@ def test_language_cookie_is_set(self):
         assert response.cookies.get(settings.LANGUAGE_COOKIE_NAME).value == ''
         assert response['Content-Language'] == site_lang
 
+    @skip_unless_lms
     @with_site_configuration(configuration={'LANGUAGE_CODE': 'es'})
     def test_preview_language_ignores_site_configuration(self):
         """