Replace DEVSTACK_GATE_ZEROMQ for DEVSTACK_GATE_MQ_DRIVER

Patch 2/2 this remove permanently the var DEVSTACK_GATE_ZEROMQ
It's necessary update jenkins job builder to reflect this change
otherwise, it will fail.
Depends on change 59995.

Change-Id: Id4c280ecbb0320c5218e8018461637aa67bf47f6
Merge "Replace DEVSTACK_GATE_ZEROMQ for DEVSTACK_GATE_MQ_DRIVER"