kubeadm join path fixed for RH linux (#4798)

roles/kubernetes/kubeadm/tasks/main.yml

@@ -70,7 +70,7 @@
 
 - name: Join to cluster if needed
   environment:
-    PATH: "{{ bin_dir }}:{{ ansible_env.PATH }}"
+    PATH: "{{ bin_dir }}:{{ ansible_env.PATH }}:/sbin"  # Make sure we can workaround RH / CentOS conservative path management
   when: not is_kube_master and (not kubelet_conf.stat.exists)
   block: