Comment 8 for bug 1733266

We should be able to filter to just the subnets that are part of the Openstack Network that we have defined in Config.

There is "network" and "external-network" which are both something like:
  The network label or UUID to bring machines up on when multiple networks exist.

Essentially when we scan subnets to record in the database we could just filter to the network id that is known.

Note that we'll want to be careful because eventually we may want to inventory all networks, but it should be a reasonable first pass fix.