prioritize first distro/arch combination for binarydeb jobs

This will let Jenkins "prefer" on distro/arch matrix build for binarydeb jobs.
Therefore we should get faster response if there is a general problem in a bigger rebuild.

Should be merged together with ros/rosdistro#2876 (so that *precise* is the priorized distro for *groovy*).

@tfoote @wjwwood Please review.