Remove temporary index for backfilling group member namespace ids
Related to !78393 (comment 836490832)
In !78393 (merged) was added a temporary index for batched background migration, we can remove this index when migration is done.
Related to !78393 (comment 836490832)
In !78393 (merged) was added a temporary index for batched background migration, we can remove this index when migration is done.