Make the setup production-ready, adjust resource allocation and optimize stuff if needed

Originally created by @Anonymous on #16436 (Redmine)

Sysadmin work

Budgeted time: 16h

Suggestions:

Give the VM one more vCPU? Sometimes the webapp (run within the apache process) and mysqld are competing for resources and there are timeouts in the web UI.
Optimize MariaDB config according to the size and usage of our database? Sometimes MariaDB is eating a full CPU core for a long time, while there’s quite some free RAM. Presumably bigger caches etc. might help.

Edited May 15, 2020 by Anonymous