Remove test cases that moved to tempest

Remove the follow three test cases that have been added (or updated if
the same case already existed) in tempest [1]:
- test_networks.NetworksTestJSON.test_show_network_fields
- test_networks.NetworksTestJSON.test_list_networks_fields
- test_networks.NetworksTestJSON.test_create_update_network_description

[1] : https://review.openstack.org/#/c/374645/

Change-Id: I919e11194939bb60be90455ed5e585cd6a894e5e
Related-Bug: #1552960
1 file changed
tree: 86e15b8e27fbf1af01b8052feb6441be49e127d4
  1. neutron/