when using the numa aware vswitches feature numa affinity is not checked when attaching interfaces to an existsing instanace

while developing https://review.opendev.org/#/c/689861
i observed that test_rebuild_server_with_network_affinity
https://review.opendev.org/#/c/689861/8/nova/tests/functional/libvirt/test_numa_servers.py@838
asserted that rebuild would fail after the numa policy required by the numa aware vswitch
feature was violated. that behaviour was due to the fact that numa affinity was not checked
as part of interface attach.

As such it was possible to violate the numa constraints and that would only become apparent if you performed a rebuild with a new image which would fail in
the numa topology filter. ideally nova should prevent the numa constraints from being violated on attach by rejecting the request.