Install the configuration required for agent registration to work

It's otherwise taken care of in the vm provisioning part but not for bare metal machines.

octo-diff happy:

*******************************************
+ File[/etc/rancher/rke2/config.yaml.d/50-snapshotter.yaml] =>
   parameters =>
     "content": "{\n  \"snapshotter\": \"native\"\n}",
     "group": "root",
     "mode": "0644",
     "owner": "root"
*******************************************
+ File[/etc/rancher/rke2/config.yaml.d] =>
   parameters =>
     "ensure": "directory",
     "group": "root",
     "mode": "0755",
     "owner": "root"
*******************************************
+ File[/etc/rancher/rke2] =>
   parameters =>
     "ensure": "directory",
     "group": "root",
     "mode": "0755",
     "owner": "root"
*******************************************
+ File[/etc/rancher] =>
   parameters =>
     "ensure": "directory",
     "group": "root",
     "mode": "0755",
     "owner": "root"
*******************************************

Refs. swh/infra/sysadm-environment#5032 (closed)