This changes up devstack code to make sure OVS does the right thing
after upgrading. After the neutron upgrade, it uses a new OVS tag for
networking, so this changes things over to the new one.
Make sure that we remove all resources that were created during
resources phase.
Set tempest fixed_network_name explicitly as it is prerequirement for
ironic, see reference.
Reference:
https://github.com/openstack/tempest/blob/039b2fe/tempest/scenario/manager.py#L1161
Change-Id: I35789602fb542bb33533211a742c3e4d265a3b91
c1e0fece35