ci-dockerfiles-sanity-check: Add workspace-cleanup "publisher"

We're regularly hitting situation when 2 docker-related jobs are running
on the same EC2 builder, and 2nd fails due to out of disk space. Try
to alleviate this using this post-build action (which goes into "publishers"
department per Jenkins Job Builder).

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I71114e11d3f9211748d4e5da556b38a514366606
1 file changed