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.

Bug: 770408
Change-Id: I4ca6391291e7b0755c78af453c3d006ad3666a17
Reviewed-on: https://chromium-review.googlesource.com/991053Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>