This adds the ability to submit the CL only if the number of commits is over a certain threshold.

No-Try: True
Bug: chromium:892545
Change-Id: I70f12e63be6d26d101b81da1f9b3e80131bcbd16
Reviewed-on: https://chromium-review.googlesource.com/c/1273243Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Commit-Queue: Oleh Prypin <oprypin@chromium.org>