Gate fix: Cap nova-network tests at Queens

Nova is working on removing the nova-network only
compute REST APIs in the Rocky release, which means
any requests to those APIs after Queens will result
in a 410 response, regardless of microversion or
whether or not neutron is being used.

The os-virtual-interfaces API is being removed in
nova change: https://review.openstack.org/569923/

As a result, os-virtual-interfaces tests will no longer
works against Rocky+ versions of nova.

nova-network tests are skipped by adding
`depends_on_nova_network = True` to the test class. The
base compute API class does a check to determine, based
on the max compute API microversion, which release is
being tested and if Rocky+ the nova-network specific
tests will be skipped.

Subsequent nova-network specific tests will be skipped
as the API removal changes are proposed in nova.

Related to blueprint remove-nova-network

Change-Id: I1d8d9aba6f44ee451e8e4d93a3e5bf5e70f7bbb3
4 files changed