nova.instances table includes soft-deleted records for long time

Issue

• Many records about deleted instances remains in nova.instances table in overcloud controller mariadb for long time.

$ sudo docker exec -t $(sudo docker ps -f name=galera -q) mysql -uroot -e "select count(*) from nova.instances where deleted_at is not NULL;"

• We see no errors in /var/log/nova/nova-rowsflush.log, which means that archiving job run succesfully.