warning: SASL authentication failure: cannot connect to saslauthd server: No such file or directory
Restart saslauthd service by running:
systemctl restart saslauthd
Check for the out put of:
mariadb.service: Found left-over process 18283 (mysqld) in control group while starting unit. Ignoring.
Check on this process as well.
I would simply check configuration file(s) for MariaDB and its
socket directive and made sure that the path is accessible (has correct permissions) and actually exists.
As an extra measure try rebooting your server.
Note: You might face this issue again in the future, and I assume the solution would be is to increase RAM or re-configure your services accordingly -