Add price tracking desktop expansion experiment to field trial testing

config

This CL also remove expired EnableShoppingListDesktop study.

Change-Id: I799344cc931b1e55732a3485b1ae0bd2b00f0bbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5421461


Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Qi Bao <qib@google.com>
Reviewed-by: Yulun Zeng <yulunz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282775}