Use VPN devstack plugin in heat jobs
Use VPN devstack plugin in heat jobs

Move away from q-vpn service in heat functional jobs, to use
neutron-vpnaas devstack plugin instead.

Change-Id: Iaaf0abfd8ca5b303d9fce05ba00a2fcdb8d351b6
Closes-Bug: #1527499

Tesora/tesora-project-config,dongwenjuan/project-config,openstack-infra/project-config,dongwenjuan/project-config,Tesora/tesora-project-config,openstack-infra/project-config