As I mentioned in D9304 it turns out we can totally just pass --performance-schema to mariadb. I was misled by some old MySQL (not MariaDB) docs as well as a comment someone left on GitHub that inaccurately stated that performance-schema had to be defined in a .cnf file and couldn't be passed as command line argument when started up. Annoying, but this is a much cleaner solution anyways.
Depends on D9304