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: I2e4ebb963ea917a6eeb2336935b7d8a02c384d31

openstack/ceilometer,openstack/ceilometer