Run all dsvm jobs from juno onwards on trusty

We have trusty slaves, we have trusty workers registered in gearman,
make zuul use them for everything newer than icehouse when running dsvm
jobs.

Change-Id: Iae037e6c1853aee5044c8e8549d8b6dc93db2b02
Merge "Run all dsvm jobs from juno onwards on trusty"