The LUCI environment alreadly does `git retry` style retries by virtue
of it's Go git-wrapper program. No need to put an extra python
interpreter in the middle.

R=hinoka@chromium.org, nodir@chromium.org

Recipe-Nontrivial-Roll: infra
Recipe-Nontrivial-Roll: build
Change-Id: I2918d7f413dde667fccd45c83ad6f4b96c2afe2e
Reviewed-on: https://chromium-review.googlesource.com/c/1292236
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Ryan Tseng <hinoka@chromium.org>