networking-midonet: remove v2 grenade job from master
networking-midonet: remove v2 grenade job from master

gate-grenade-dsvm-networking-midonet-v2-ubuntu-xenial examines
an upgrade scenario from v2 monolithic plugin to ml2.
Because v2 monolithic plugin has been removed in Pike cycle,
This job will stop working on master once branches for grenade
jobs are updated for Pike. [1]

[1] Ifb7f7c336523f86fd7a2c18def2ddbbbf656f2fb

Closes-Bug: #1710236
Change-Id: I3a8b6444b79ab1e4088cd1a8d6e7ae51451db87c

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