Add all monitoring hosts to the NRPE config of a monitoring host

There is an issue with the logic currently used to fill the mon_host array. Currently only 127.0.0.1 and the IP address of the monitoring host itself will be put in the NRPE config of a monitoring host.

The code that is causing this is duplicated further down in the recipe to make sure a monitoring host has its own IP on the allow list.

I've changed the recipe so now all clients, including the monitoring host itself, will search for hosts with the monitoring role.