Remove neutron cherry pick to disable ipset

Removes cherry pick for https://review.openstack.org/#/c/121434/
which got a -2 (so I abandoned it).

TripleO works now with ipset because we landed
https://review.openstack.org/#/c/121435/ instead which
simply installs the ipset package.

Change-Id: I03301091b041c60dfbe5ac93810fbfeb35d0e671