pkg/backup: Don’t backup MariaDB if it’s not running
pkg/backup: Don’t backup MariaDB if it’s not running

If a user intentionally scaled MariaDB to zero, we should not attempt to
take a backup from it.

Closes #2594

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>
lmars/flynn,benbjohnson/flynn,benbjohnson/flynn,philiplb/flynn,philiplb/flynn,benbjohnson/flynn,benbjohnson/flynn,flynn/flynn,philiplb/flynn,flynn/flynn,philiplb/flynn,lmars/flynn,flynn/flynn,flynn/flynn,lmars/flynn,philiplb/flynn,lmars/flynn,benbjohnson/flynn,lmars/flynn,flynn/flynn,benbjohnson/flynn