Check kube-apiserver up on all masters before upgrade (#7193)

Only checking the kubernetes api on the first master when upgrading is not enough.
Each master needs to be checked before it's upgrade.

Signed-off-by: Rick Haan <rickhaan94@gmail.com>

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']|first
+  when: inventory_hostname == groups['kube-master']
   register: _result
   retries: 60
   delay: 5