Fix public VIP gateway ping for neutron

We have different network scheme in astute.yaml for neutron. This
patch fixes public gateway calculation for pacemaker "ping"
resource when we use neutron.

Closes-bug: 1373375
Change-Id: Ia49ba52d3eab5dd5733450901e7a84a3448dbd3d
Merge "Fix public VIP gateway ping for neutron"