Content-Range header values are not validated and enforced

[BenWhitehead]

Environment details

• testbench version 0.45.0

Steps to reproduce

1. Retry conformance test http-7-[return-503-after-256K]-storage.objects.insert-50
2. Full http log: https://gist.github.com/BenWhitehead/ae8a02958ff22e1e238057fed3732a15#file-http-log-L104
3. Notice on like 104 Content-Range: bytes 262144-786431/524288, the end of that range is larger than the specified total number of bytes.
4. Originally discovered while investigating Core: Seeing unexpected exception during upload to GCS with Java client java-storage#2770