Allow kubeadm master untaint to fail (#3549)

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

@@ -215,3 +215,4 @@
   command: "{{ bin_dir }}/kubectl taint node {{ inventory_hostname }} node-role.kubernetes.io/master:NoSchedule-"
   delegate_to: "{{groups['kube-master']|first}}"
   when: inventory_hostname in groups['kube-node']
+  failed_when: false