fix: show staff tag for global staff in discussion forum

Author: Alam-2U

lms/djangoapps/discussion/rest_api/serializers.py

@@ -83,6 +83,7 @@ def get_context(course, request, thread=None):
     course_staff_user_ids = get_course_staff_users_list(course.id)
     moderator_user_ids = get_moderator_users_list(course.id)
     ta_user_ids = get_course_ta_users_list(course.id)
+    global_staff_user_ids = list(User.objects.filter(is_staff=True).values_list('id', flat=True))
     requester = request.user
     cc_requester = CommentClientUser.from_django_user(requester).retrieve(
         course_id=course.id
@@ -104,6 +105,7 @@ def get_context(course, request, thread=None):
         "moderator_user_ids": moderator_user_ids,
         "course_staff_user_ids": course_staff_user_ids,
         "ta_user_ids": ta_user_ids,
+        "global_staff_user_ids": global_staff_user_ids,
         "cc_requester": cc_requester,
         "has_moderation_privilege": has_moderation_privilege,
         "is_global_staff": is_global_staff,
@@ -273,7 +275,7 @@ def _get_user_label(self, user_id):
         Returns the role label (i.e. "Staff", "Moderator" or "Community TA") for the user
         with the given id.
         """
-        is_staff = user_id in self.context["course_staff_user_ids"]
+        is_staff = user_id in self.context["course_staff_user_ids"] or user_id in self.context["global_staff_user_ids"]
         is_moderator = user_id in self.context["moderator_user_ids"]
         is_ta = user_id in self.context["ta_user_ids"]