Resolve evaluation of bifrost-keystone-client-config

The owner parameter for some of the tasks for the Keystone
client configuration does not have a default fallback, which
results in a failure if SUDO_USER is not set in the environment.

This patch adds the missing default fallbacks so that it can safely
evaluate to root if it missing from the environment.

Related-Bug: #1674483

Change-Id: I31a2a33e2fb3b004dfec179426c7d1b4c72301d2

playbooks/roles/bifrost-keystone-client-config/tasks/main.yml

@@ -35,12 +35,12 @@
   file:
     name: "~{{ user | default('root') }}/.config/openstack"
     state: directory
-    owner: "{{ user }}"
+    owner: "{{ user | default('root') }}"
     mode: 0700
 
 - name: "Write clouds.yaml configuration from template"
   template:
     src: clouds.yaml.j2
     dest: "~{{ user | default('root') }}/.config/openstack/clouds.yaml"
-    owner: "{{ user }}"
+    owner: "{{ user | default('root') }}"
     mode: 0600