Changelog trims updates from a given RID even if a consumer has not received any of them

[tbordaz]

Issue Description
If a consumer has not received any of the updates from a given RID, the RUV (in the replication agreement) contains no csn. In such case, the changelog trimming thread compute the starting purge csn using the supplier RUV instead of the RA RUV. Later the supplier will miss this csn to update the consumer and replication is broken

Package Version and Platform:

• all versions
  Steps to Reproduce

Steps to reproduce the behavior:

1. script shell allows to reproduce it systematically. Need to translate it into CI

Expected results
supplier should keep the CSN that have not yet been seen by a consumer

Additional context
Add any other context about the problem here.