Fix Flexvolume mount in Openstack Controller (#6480)

roles/kubernetes-apps/external_cloud_controller/openstack/templates/external-openstack-cloud-controller-manager-ds.yml.j2

@@ -70,7 +70,7 @@ spec:
       hostNetwork: true
       volumes:
       - hostPath:
-          path: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
+          path: "{{ kubelet_flexvolumes_plugins_dir }}"
           type: DirectoryOrCreate
         name: flexvolume-dir
       - hostPath: