Test jobs often fail because buildset-registry
starts in the very beginning of the buildset
and then it takes a while to build images and then
run the deployment tests.
Fortunately building images takes about an hour
even taking into account waiting in the queue.
And then in most cases during the deployment job
images are consumed before the buildset-registry
job times out.
So setting the buildset-registry job non-voting
can help to avoid POST_FAILURE.
Change-Id: Ibe4726b4c89c281e9234d2e495c8ed50a008c8aa
9c19b92dea