tests: fetch unshared subnetpools only
tests: fetch unshared subnetpools only

This will allow us to avoid races in api tests where other tests create
shared pools and in that way influence the resulting list of resources
we fetch to compare with shared=False list later.

Change-Id: Ic3c35293d18fee0db01ebbab532ec6b8f32f9b14

huntxu/neutron,mahak/neutron,sebrandon1/neutron,mahak/neutron,noironetworks/neutron,noironetworks/neutron,eayunstack/neutron,igor-toga/local-snat,huntxu/neutron,openstack/neutron,cloudbase/neutron,cloudbase/neutron,mahak/neutron,openstack/neutron,openstack/neutron,sebrandon1/neutron,eayunstack/neutron,igor-toga/local-snat