This reverts commit 8840d622.

Reason for revert: This requires the infra-side to be adapted to look
for open rolls. There's no such feature in the gerrit recipe_module
or git-cl tooling yet.

Original change's description:
> [release] Make gerrit the default for all release tools
> 
> This switches also the V8->Chromium rolls to Gerrit.
> 
> NOTRY=true
> TBR=hablich@chromium.org
> 
> Bug: chromium:685318
> Change-Id: Idc168f790541f09bd2f2d7c2f72806ac9e966843
> Reviewed-on: https://chromium-review.googlesource.com/558913
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#46388}

TBR=machenbach@chromium.org,hablich@chromium.org,tandrii@chromium.org

Change-Id: I597538b6165b9952b5df9cde72466b95739cf56b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:685318
Reviewed-on: https://chromium-review.googlesource.com/558225Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46390}