soft_deactivation: Do not bother to fetch stream data as well.

This prefetch is unnecessary and makes this query load more data than
needed.

Existing tests verify that this does not add more queries.

zerver/lib/soft_deactivation.py

@@ -176,8 +176,7 @@ def add_missing_messages(user_profile: UserProfile) -> None:
     # meantime.  Without that tiebreak, we could end up incorrectly
     # processing the ordering of those two subscription changes.
     subscription_logs = list(
-        RealmAuditLog.objects.select_related("modified_stream")
-        .filter(
+        RealmAuditLog.objects.filter(
             modified_user=user_profile, modified_stream_id__in=stream_ids, event_type__in=events
         )
         .order_by("event_last_message_id", "id")