Revert "cbuildbot: Use buildbucket for remote tryjobs by default."

This reverts commit fee287427456fba157a9d56fec9acb60898e4e8e.

Reason for revert: Break pre-cq-launcher #8925

Original change's description:
> cbuildbot: Use buildbucket for remote tryjobs by default.
> 
> Remove --use-buildbucket option, and replace it with
> --do-not-use-buildbucket option.
> 
> We want to use bucketbucket to schedule all tryjobs by default. We
> haven't been able to find out for certain if there is anyone who needs
> buildbucket permissions for this that doesn't already have them,
> so.... let's find out!
> 
> A PSA has been sent out asking for feedback from anyone required to
> use --do-not-use-buildbucket to run a tryjob.
> 
> This CL was submitted as CL:462518, and reverted as CL:464309.
> 
> BUG=chromium:671848
> TEST=run_tests
> 
> Change-Id: I92f9137aa7cd4807a2b9006f357bf2189c2c0767
> Reviewed-on: https://chromium-review.googlesource.com/465488
> Commit-Ready: Don Garrett <dgarrett@chromium.org>
> Tested-by: Don Garrett <dgarrett@chromium.org>
> Reviewed-by: Ningning Xia <nxia@chromium.org>
> 

TBR=dgarrett@chromium.org,nxia@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:671848

Change-Id: Ib690af4dc6efabdf4c2445657f3e0c31a9f9ff79
Reviewed-on: https://chromium-review.googlesource.com/467026
Reviewed-by: Chun-ta Lin <itspeter@chromium.org>
Commit-Queue: Chun-ta Lin <itspeter@chromium.org>
Tested-by: Chun-ta Lin <itspeter@chromium.org>
Trybot-Ready: Chun-ta Lin <itspeter@chromium.org>
2 files changed