Skip gathering facts when reset_nodes is false

The doc[1] explains we need to specify

  "-e reset_nodes=false -e allow_ungraceful_removal=true"

to delete offline node. However the task "Gather facts"
trid to gather facts of offline node also and the task
was failed.
This adds a condition to skip gathering facts when reset_nodes
is false on remove-node.yml.

This change comes from @acainelli's comment, thank you @acainelli!

[1]: https://github.com/kubernetes-sigs/kubespray/blob/master/docs/nodes.md#3-remove-an-old-node-with-remove-nodeyml

remove-node.yml

@@ -30,6 +30,7 @@
 
 - name: Gather facts
   import_playbook: facts.yml
+  when: reset_nodes|default(True)|bool
 
 - hosts: "{{ node | default('kube_node') }}"
   gather_facts: no