Fix apiserver port when upgrading (#6136)

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

 ---
 - name: kubeadm | Check api is up
   uri:
-    url: "https://{{ ip | default(fallback_ips[inventory_hostname]) }}:6443/healthz"
+    url: "https://{{ ip | default(fallback_ips[inventory_hostname]) }}:{{ kube_apiserver_port }}/healthz"
     validate_certs: false
   when: inventory_hostname == groups['kube-master']|first
   register: _result