Move configuration of servers completely to ansible

With this change we no longer use user-data scripts on the provided
machines. That makes it way easier for me to handle all the
configuration, since I only have to run ansible. Furthermore this the
burdon to think what may went wrong, since ansible is easier to debug
than some arbitrary scripts which run at provisioning-time on the
machines.

With this change I should also think about restructuring the code a bit
as well. Since it's actually easier to provide the initial
software-stack for the cluster via ansible than via terraform, at least
as far as I can tell right now.

k3s/roles/agent-setup/templates/nic.network.j2

@@ -0,0 +1,5 @@
+[Match]
+Name={{ target_nic }}
+[Network]
+DHCP=yes
+Gateway={{ private_nat }}