Remove unused URL.

openedx/features/course_experience/urls.py

@@ -58,11 +58,6 @@ urlpatterns = [
         LatestUpdateFragmentView.as_view(),
         name='openedx.course_experience.latest_update_fragment_view',
     ),
-    url(
-        r'course_sock_fragment$',
-        CourseSockFragmentView.as_view(),
-        name='openedx.course_experience.course_sock_fragment_view',
-    ),
     url(
         r'^dismiss_welcome_message$',
         dismiss_welcome_message,