Add test for the validate auto_allocated_topology API

This new test calls neutron API to check requirements for the auto
allocated topology and to make sure that it don't returns 404 for
example.

Depends-On: https://review.opendev.org/c/openstack/neutron/+/920360
Depends-On: https://review.opendev.org/c/openstack/neutron/+/920481
Depends-On: https://review.opendev.org/c/openstack/neutron/+/920482

Related-bug: #2066369
Change-Id: I9b46699cdf9361a49e558130b336722599419f0f
2 files changed