Ticket 49671 - Readonly replicas should not write internal ops to changelog
Bug Description: When a hub receives an update that triggers the memberOf
plugin, but that interal operation has no csn and that
causes the update to the changelog to fail and break
replication.
Fix Description: Do not write internal updates with no csns to the changelog
on read-only replicas.
https://pagure.io/389-ds-base/issue/49671
Reviewed by: simon, tbordaz, and lkrispen (Thanks!!!)
(cherry picked from commit afb755bd95f1643665ea34c5a5fa2bb26bfa21b9)