50-mariadb_safe.cnf was only ever intended to be a reference file.
With mariadbd-safe falling into disuse in Debian since systemd became
a service it was assumed this files wasn't used except on a few old
legacy init systems. Its assumed these users will have a configuration
already set.

It is however read by the mariabackup galera-sst script. This forks
off the logger process to write the output to /dev/log, which on a
systemd service the journalctl is reading anyway.

The real harm is on containers where there is now a MariaDB operator
that runs Galera based containers. In containers there is no /dev/log,
so information gets lost.

It would be much more direct just to go straight to stdout/error
like what would happen without this configuration.

Rather than risk the galera-sst scripts moving to the [mariadbd-safe]
group name introduced in a1211a4e, we
remove the file for cleanness.