[autotest] Record log for abort_suite

Currently, it's impossible to debug whether a suite is aborted
by builder or by lab bug.
Record log in abort_suite module so that we can track back when
a suite is aborted via the module.

BUG=chromium:440905
TEST=./site_utils/abort_suite.py -s dummy -i nyan_big-release/R38-6029.0.0

Change-Id: Ief636ebe547b47db4b563b81edb9147acf1afea4
Reviewed-on: https://chromium-review.googlesource.com/234436
Reviewed-by: Fang Deng <fdeng@chromium.org>
Tested-by: Mungyung Ryu <mkryu@google.com>
Commit-Queue: Mungyung Ryu <mkryu@google.com>
3 files changed