[aioaws] Fix S3MultiPartCreate (#10938)
[aioaws] Fix S3MultiPartCreate (#10938)

We are not permitted more than 10,000 parts. Moreover a tiny copy part size
seems to have negative consequences on throughput.
hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail