cbuildbot: run network tests in signer precq

Since the network based tests in the signer are not onerous, run them
as part of the pre-cq.  Since they'll be run in parallel with the rest
of the big tests, it shouldn't slow things down either.

BUG=chromium:673906
TEST=ran the signer precq config against this

Change-Id: I6b6fbebaca8cc7845e03f0325ea86f2e6519480a
Reviewed-on: https://chromium-review.googlesource.com/439924
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed