Add nodepool-xenial.yml file
Add nodepool-xenial.yml file

To run Beaker jobs in OpenStack Infra, we need this file so we run tests
on the right nodeset

Change-Id: Ib52e196bfb830ed57d297103cad1c34ca9628ecb

openstack/puppet-trove,openstack/puppet-trove,openstack/puppet-trove