Switching discussion ids to use UNIQUE_ID XBlock sentinel

common/lib/xblock/discussion/discussion_forum/discussion_forum.py

 import logging
 
 from xblock.core import XBlock
-from xblock.fields import Scope, String
+from xblock.fields import Scope, String, UNIQUE_ID
 from xblock.fragment import Fragment
 
-from uuid import uuid4
 
 from .utils import (
     render_template,
@@ -21,7 +20,7 @@ class DiscussionXBlock(XBlock):
     """ Provides functionality similar to discussion XModule in inline mode """
     FIELDS_TO_INIT = ('discussion_id',)
 
-    discussion_id = String(scope=Scope.settings, default=lambda: uuid4().hex)
+    discussion_id = String(scope=Scope.settings, default=UNIQUE_ID)
     display_name = String(
         display_name="Display Name",
         help="Display name for this module",