Retrieving that information for every network can take considerable time
on large deployments with large number of networks, and for some kinds
of network drivers (ovn binary) this will be always zero anyways.
This setting lets us disable that column to speed up the networks view.
Change-Id: I1f1561916067d3f4a02f10ec9f62e8ba777a1501
1ea4f4d76f