move flexvolume plugin directory creation to preinstall (#4999)

* move flexvolume plugin directory creation to preinstall

* changes per pr feedback

roles/kubernetes/preinstall/tasks/0040-set_facts.yml

@@ -178,3 +178,13 @@
     etcd_deployment_type: host
   when:
     - etcd_kubeadm_enabled
+
+- name: check /usr readonly
+  stat:
+    path: "/usr"
+  register: usr
+
+- name: set alternate flexvolume path
+  set_fact:
+    kubelet_flexvolumes_plugins_dir: /var/lib/kubelet/volumeplugins
+  when: not usr.stat.writeable