Change Observer: Use '.any.js' WPTs instead of setting up workers

Uses testharness's global metadata comment for '.any.js' files instead
of creating individual tests for each global type which sets up its own
worker.

R==dslee@chromium.org

Bug: 341136316
Change-Id: I9fe8398c4b785c4bc329f0ccc3e64397f87641c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5743827
Commit-Queue: Nathan Memmott <memmott@chromium.org>
Reviewed-by: Daseul Lee <dslee@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1335089}