refactor(k3s): centralize k3s primary server IP and integrate Netcup DNS

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

vars/docker.ini

@@ -1,10 +1,10 @@
 [docker_host]
-docker-host01 ansible_become_pass="{{ vault.docker.host01.sudo }}"
+docker-host01 ansible_become_pass="{{ vault_docker.host01.sudo }}"
 docker-host10
 docker-host12
 
 [docker_lb]
-docker-lb ansible_become_pass="{{ vault.docker.lb.sudo }}"
+docker-lb ansible_become_pass="{{ vault_docker.lb.sudo }}"
 
 [docker]