Added context for "*mariadb*" named executables
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Since MariaDB 10.4, the upstream added "*mariadb*" named symlinks for "*mysql*" named executables.
https://jira.mariadb.org/browse/MDEV-17591
Since MariaDB 10.5, the upstream switched them, so the executables are now "*mariadb*" named and the symlinks are "*mysql*" named.
https://jira.mariadb.org/browse/MDEV-21303
Without these SELinux rules, the new "*mariadb*" files haven't got a correct context.