[ci] upload test stats to s3 instead of rockset directly (#80593)
Previously we were writing documents to Rockset directly using the write
API. This turned out to be a source of issues, occupying Rockset leaf
CPU and making other queries timeout. Also, we are starting to get rate
limited by Rockset, leading to data loss.
Instead, write test stats to s3 and let Rocket's managed integration
sync it. This appears to be significantly more efficient, and should
solve our throughput issues fundamentally.
Hopefully we can re-enable per-PR stats after this change, but let's see
how it does first.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80593
Approved by: https://github.com/janeyx99
