Update the S3 benchmark for correctness and performance (#2838)

## Motivation and Context
Gain a better understanding of S3 performance with the Rust SDK

## Description
Updates the S3 benchmark to:
1. Add verify step (untimed)
2. Improve performance by reading and writing from the disk concurrently
3. Add support for using multiple clients simultaeneously
4. Fix correctness issues & simplify
5. Add timeouts on the parts

## Testing
Ran the benchmark locally and on a c5n.18xlarge


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