Choose ovn env file based on OSP release
Choose ovn env file based on OSP release

In OSP 13 we are using ovn env file from services-docker and not
services as it is now.

Change-Id: Ia84109a822d70bf109339da06c9c24a45fff46e5

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared