Android perf tests: add temp-based throttling to pixel6 bots. Seems like we don't have sufficient airflow to run heavy tests at full throttle. Some shards start >10C hotter, so add custom throttling to avoid aggressive throttling by the phone itself skewing perf results. This might noticeably increase shard runtime on bots with poor airflow. Implementation is similar to https://crrev.com/c/5288455 but relies on data available on current bot OS build (no IThermal) and does _not_ disable phone throttling. Bug: b/345514719 Change-Id: I582838c2448c9b014381a4f8ba847343b68e4d3a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5608312 Commit-Queue: Roman Lavrov <romanl@google.com> Reviewed-by: Cody Northrop <cnorthrop@google.com>