Check nameserver when dns is enable (kubernetes-sigs#10561)

roles/kubernetes/preinstall/tasks/0020-set_facts.yml

@@ -91,6 +91,7 @@
     - configured_nameservers is defined
     - not (upstream_dns_servers is defined and upstream_dns_servers | length > 0)
     - not (disable_host_nameservers | default(false))
+    - dns_mode in ['coredns', 'coredns_dual']
 
 - name: NetworkManager | Check if host has NetworkManager
   # noqa command-instead-of-module - Should we use service_facts for this?