[toolchain-utils] Remove --do-not-use-buildbucket flag

This implements the correct way to find the remote description so
that we do not need to disable the buildbucket authentication.

BUG=chromium:711430
TEST=Launched nightly buildbot job and it was able to find correct
build log.

Change-Id: I0a2e16ec284bae46af684daf3abcbbea1b9c3fe9
Reviewed-on: https://chromium-review.googlesource.com/478010
Commit-Ready: Caroline Tice <cmtice@chromium.org>
Tested-by: Caroline Tice <cmtice@chromium.org>
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
1 file changed