Symmetricaly test dib and ironic

The tempest-dsvm-virtual-ironic job relies on diskimage-builder to create
the deploy ramdisk which is used by the PXE driver during this test. Since this
test is now voting on Ironic, it should also be voting on diskimage-builder
to avoid asymmetrically gating one project but not the other.

Change-Id: Ie5b55019095dc20888cbc327023afce058120037
Merge "Symmetricaly test dib and ironic"