Add a new unauthenticated ingress to check the status of ircrelay

Instead of [1], we can then adapt the icinga check to hit this endpoint which should return "OK" [2]

[1] swh/infra/puppet/puppet-swh-site!638 (closed)

[2] swh/infra/puppet/puppet-swh-site!639 (merged)

Refs. swh/infra/sysadm-environment#4525