Rename the win8_chromium_gn_upload bot.

R=iannucci@chromium.org

Change-Id: I00401bbd710e2c80fab6571a1a555925259511a9
Reviewed-on: https://chromium-review.googlesource.com/726559
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#509950}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 965d239e5b63936a0ff2ba8543f17dc06d72b081