use the settings for new tree status app

From documentation: https://chromium.googlesource.com/infra/gerrit-plugins/chumpdetector/+/HEAD/README.md

Change-Id: Ib75d28a799cd929aa0673b036e15a9fcd7aa7f0b
Reviewed-on: https://chromium-review.googlesource.com/c/infra/+/5659348
Reviewed-by: Gavin Mak <gavinmak@google.com>