deploy alertmanager-irc-relay on `prometheus1`

IRC notifications will be sent to the #tor-bots and #tor-monitoring channels. At first we'll experiment with only sending critical notifications there, but if we're missing out on notifications, we might send warning notifications to those channels and send critical notifications to the main #tor-admin channel.

The alertmanager-irc-relay endpoint is currently in testing in anarcat's lab, and the results are not fantastic, more research and tuning is required to get an acceptable level.