Transaction savepoint may cause failure in galera replaying

transaction savepoint statement inserts a corresponding query log event in binlog. Galera replication is not supposed to handle statement based replication events, but apparently this simple event goes well through galera replication nevertheless. But, otoh, if such transaction with savepoint has to replay in the sending node, the replaying may fail for missing character et information.

This issue surfaced as part of MDEV-29684 testing, where the RQG grammar contains savepoints and causs replaying as well