The "sent" replication log might not be stored

Regression caused by REPLICAT-123.

If actually sending the message is slower than storing the "stored" replication log entry, you can end up in a race condition where the "sent" replication log is not stored.

The reason for this race condition is an optimization added to avoid re-storing logs when re-sending an old message to a requesting instance.

But honestly while it make sense to prevent re-storing the "stored" log there is no reason to prevent it for the "sent" entry since a message was sent, and it does make sense to store log for it.