Zuul: add file extension to playbook path
Zuul: add file extension to playbook path

Zuul now supports including the file extension on the playbook path
and omitting the extension is now deprecrated.  Update references
to include the extension.

Change-Id: I20ba78bf500be8cb745badc69757da8d5644c551

openstack/sahara-image-elements,openstack/sahara-image-elements