FIX: Unneded (extra) cycles in some tasks (#1393)

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

@@ -6,6 +6,7 @@
   delegate_to: "{{item}}"
   with_items: "{{groups['kube-master']}}"
   when: needs_etcd_migration|bool
+  run_once: true
 
 - name: "Post-upgrade | Pause for kubelet stop"
   pause:
@@ -19,6 +20,7 @@
   delegate_to: "{{item}}"
   with_items: "{{groups['kube-master']}}"
   when: needs_etcd_migration|bool
+  run_once: true
 
 - name: "Post-upgrade | etcd3 upgrade | purge etcd2 k8s data"
   command: "{{ bin_dir }}/etcdctl --endpoints={{ etcd_access_addresses }} rm -r /registry"