CIPAAS-347 Use a hostPath to let DNSLB health checks know when container shutting down

Currently if a container is shutting down for other reasons than pod terminating (e.g. restart due to liveness probes failing), this is not taken into account by the DNSLB integration health checks.

To be merged after https://gitlab.cern.ch/ai/it-puppet-hostgroup-paas/merge_requests/113 is merged and deployed in prod

Also fix v6 mode detection for the Forwarded headers.