Provision file-zfs test node in gstg
Using the new single-disk config.
Add commented out file-zfs-single-zone, as we may not need it and some resources (firewall rules) are provisioned for the module even with node_count=0.
This is (rather cheekily) already provisioned, before review. It was a re-run of a previously accepted test instance provision with a different ZFS config, so I did this to test that the config worked.