Modify the permission of directory

Considering the safety, 644 is enough
other user is not necessary to having write permission.
adding 'su' in where needs writing permissions is a good practice
this operation is safer.

Change-Id: I45d0c6e5ef7338f93db21cf4ef58b4a4fd831210

ansible/roles/baremetal/tasks/pre-install.yml

@@ -132,6 +132,6 @@
     path: "{{ node_config_directory }}"
     state: directory
     recurse: yes
-    mode: 0666
+    mode: 0644
   become: True
   when: create_kolla_user | bool == False