Adjust task name since we allow empty kube_node (#11474)

roles/kubernetes/preinstall/tasks/0040-verify-settings.yml

 ---
-- name: Stop if either kube_control_plane or kube_node group is empty
+- name: Stop if kube_control_plane group is empty
   assert:
     that: groups.get( 'kube_control_plane' )
   run_once: true