Ticket 49020 - v1.2.11 do not treat missing csn as fatal
    
            This patch removes the automatic choice of an alternative csn when
            the calculated anchor csn is not found.
    
            In that case it does no longer go to fatal state but will retry later.
    
            It also adds a configuration parameter to thr replication agreement to
            allow to pick a "next best" anchorcsn if the original is not found to
            keep replicatio going.
    
            Reviewed by: Noriko, William