"git_setup.py" does not use "logging". Remove it.

BUG=None
TEST=None
R=iannucci@chromium.org

Change-Id: Ia31882966bac056899308a67284f8fde15c7b0e0
Reviewed-on: https://chromium-review.googlesource.com/569101Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>