[ez] Remove unused code in upload_test_stats (#111504)
This is code related to parallelism and test times that isn't used, so remove it.
Tested by running locally with `python3 -m tools.stats.upload_test_stats --workflow-run-id 6551035874 --workflow-run-attempt 1 --head-branch main --head-repository "pytorch/pytorch"` and commenting out parts for uploading to s3.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111504
Approved by: https://github.com/huydhn
