This reverts commit f3eed001.

Reason for revert: Some PRESUBMIT checks still expect 
CheckRietveldTryJobExecution to exist.

Original change's description:
> Remove Rietveld support from presubmit
> 
> Since no one can upload or land changes from Rietveld anymore,
> PRESUBMIT and its support files no longer need to be able to
> support it.
> 
> R=​tandrii@chromium.org
> 
> Bug: 770408
> Change-Id: I749092b66fdca16d5cef77e8cefc905aa5375b50
> Reviewed-on: https://chromium-review.googlesource.com/693380
> Commit-Queue: Aaron Gable <agable@chromium.org>
> Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>

TBR=agable@chromium.org,tandrii@chromium.org

Change-Id: I72e29bd8a9739406f29190adbeb7eb7718ed21cd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 770408
Reviewed-on: https://chromium-review.googlesource.com/991012
Commit-Queue: Aaron Gable <agable@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>