Remove incorrect filter on listing subnets

The test case uses 'admin_state_up' as a filter parameter on listing
subnets, but this is an invalid filter since the subnet resource
doesn't have this attribute. This patch removes this filter.

Change-Id: I3f2e6e861adaeef81a1a5819a57b28f5c6281d80
Related-Bug: #1749820
1 file changed