- Use latest slapos.toolbox (0.41.0)
- stack/erp5/buildout.cfg add script is-local-tcp-port-opened
- Change instance-mariadb promise to use is-local-tcp-port-opened

The monitor runs promises every 5 minutes.
The previous mariadb promise check for listening tcp port by openning
a socket and closing it, causing mariadb to block the host after a
defined amount of time.

The new script `is-local-tcp-port-opened` checks for opened tcp port
on current machine by reading /proc/net/tcp{,6}. No socket is opened.
Maria should not block hosts anymore.