Fix "api is up" check (#7295)

Signed-off-by: Etienne Champetier <e.champetier@ateme.com>
(cherry picked from commit 662a37ab4f)

roles/kubernetes/master/tasks/kubeadm-upgrade.yml

@@ -3,7 +3,7 @@
   uri:
     url: "https://{{ ip | default(fallback_ips[inventory_hostname]) }}:{{ kube_apiserver_port }}/healthz"
     validate_certs: false
-  when: inventory_hostname == groups['kube-master']
+  when: inventory_hostname in groups['kube-master']
   register: _result
   retries: 60
   delay: 5