Skip testMaximumMultipartUpload for remote backend
Skip testMaximumMultipartUpload for remote backend

This test dominates run-time due to issuing 10,000 RPCs.

timuralp/s3proxy,andrewgaul/s3proxy,kahing/s3proxy,timuralp/s3proxy,kahing/s3proxy,andrewgaul/s3proxy