Default to 'podman' in container-puppet.py
Default to 'podman' in container-puppet.py

Similar to our t-h-t defaults we should default this script
to 'podman' for faster debugging on the command line.

Change-Id: I4e826542c24848e12abc400b1621a6b812922231

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates