mysql_upgrade_service/mariadb-upgrade-service - avoid slow shutdown if not necessary

Slow shutdown (innodb_fast_shutdown=0) is currently used by mysql_upgrade_service, during upgrade, since that was advised previously. It can take a long time, so it is better be avoided.

Tt is no more necessary . Instead. innodb_fast_shutdown=1 can be used.

We would still restart and shutdown if service was not running prior to upgrade, to avoid crash recovery in the new version.