neutron: trigger gate hooks for dvr scenario job
neutron: trigger gate hooks for dvr scenario job

Note: the job will pass the same first argument into the gate hook as
non-DVR job. We will use DEVSTACK_GATE_NEUTRON_DVR to distinguish the
flavour if needed.

Change-Id: I1fa3eaa3788a844f662adc98de1ec8d11f221d6b

openstack-infra/project-config,openstack-infra/project-config