Migrate playbooks to use 'become'

Ansible is scheduled to remove the 'sudo' module
and replace it with 'become'. Switch to using this
now since it is already supported in 1.9.

Closes-Bug: #1504535

Change-Id: Ie63816e36a95c86d54fea5f50325522b41597047

playbooks/example-deploy-all-available-nodes.yaml

@@ -19,11 +19,11 @@
 - hosts: localhost
   connection: local
   name: "Collect facts"
-  sudo: no
+  become: no
   gather_facts: yes
 - hosts: baremetal
   name: "Create configuration drive files and deploy machines from inventory"
-  sudo: no
+  become: no
   connection: local
   roles:
     - { role: bifrost-configdrives-dynamic, when: provision_state == "available" and maintenance | bool != true }