[autotest] Add a reboot test as a cleanup action.

A test that can leave a DUT in a very odd state if it fails can now
request a reboot via including the label `cleanup-reboot`, for now.

BUG=None
TEST=ran `autoserv -C --job-labels cleanup-reboot`

Change-Id: I6403b3c6362ce87d5c239622ed1c3bcc684a1af5
Reviewed-on: https://chromium-review.googlesource.com/195711
Reviewed-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
Tested-by: Alex Miller <milleral@chromium.org>
1 file changed