It prevents a crash in wsrep_report_error() which happened when appliers would run
with FK and UK checks disabled and erroneously execute plain inserts as bulk inserts.
Moreover, in release builds such a behavior could lead to deadlocks between two applier
threads if a thread waiting for a table-level lock was ordered before the lock holder.
In that case the lock holder would proceed to commit order and wait forever for the
now-blocked other applier thread to commit before.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>