fix: delay creation of course topics after course publish (#31307)

When running in a sharded MongoDB setup it's possible that querying the
modulestore right after the course publish signal will not return the
latest data.

This commit adds a delay similar to the one used in other places in the
codebase for a similar reason.

cms/djangoapps/contentstore/signals/handlers.py

@@ -142,7 +142,10 @@ def listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable=
     if CoursewareSearchIndexer.indexing_is_enabled() and CourseAboutSearchIndexer.indexing_is_enabled():
         update_search_index.delay(course_key_str, datetime.now(UTC).isoformat())
 
-    update_discussions_settings_from_course_task.delay(course_key_str)
+    update_discussions_settings_from_course_task.apply_async(
+        args=[course_key_str],
+        countdown=settings.DISCUSSION_SETTINGS['COURSE_PUBLISH_TASK_DELAY'],
+    )
 
     # Send to a signal for catalog info changes as well, but only once we know the transaction is committed.
     transaction.on_commit(lambda: emit_catalog_info_changed_signal(course_key))