Remove left over nodes_to_drain (#7412)

Signed-off-by: Etienne Champetier <e.champetier@ateme.com>

roles/remove-node/pre-remove/tasks/main.yml

 ---
-- name: remove-node | Set `nodes_to_drain` as empty list
-  set_fact:
-    nodes_to_drain: []
-
 - name: remove-node | List nodes
   command: kubectl get nodes -o go-template={% raw %}'{{ range .items }}{{ .metadata.name }}{{ "\n" }}{{ end }}'{% endraw %}
   register: nodes