Add browsertest for metrics JobScheduler background upload task

Bug: 445735421
Change-Id: I823d769b7ca2cdf8f090a531242f56f0d0002ee4
Validate-Test-Flakiness: skip
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7518604
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Luc Nguyen <lucnguyen@google.com>
Cr-Commit-Position: refs/heads/main@{#1577583}
NOKEYCHECK=True
GitOrigin-RevId: e0601cc9859c3eacb189b57105931aa852fc10e5