This provisions the node and for the first time, will trigger a puppet run.
This puppet run will install the gateway's role including the routes back/forth
between production network and the staging network.
In the provision steps, prior to call puppet, we do need to install some setup
ourselves (route, ip_forward, etc...) to allow proxmox to continue the
provisioning of other nodes (coming). Puppet run installs the equivalent
instruction to make them persistent.
Depends on D1796