alertmanager_irc_relay: Activate check on the alertmanager with expected 401
We cannot expose the check with authentication as it would appear on the icinga.s.o site (with read-only guest user). So expects a 401 instead (as other reverse proxy sites with authentication currently do).
Can't really check with octo-diff as it's a collected resource which installs the check.
Edited by Antoine R. Dumont