Make sure node_ip is set if node is in etcd group (#6720)

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

@@ -21,6 +21,8 @@
   assert:
     that: node_ip is defined and node_ip | length > 0
     msg: "Etcd node ip is not set !"
+  when:
+    - inventory_hostname in groups['etcd']
 
 - name: Lookup etcd member id
   shell: "{{ bin_dir }}/etcdctl member list | grep {{ node_ip }} | cut -d, -f1"