The existing test measures latencies of object GET-s. That's nice (though incomplete), but we want to measure upload performance. Here it is.
refs: #22460Closesscylladb/scylladb#22480
* github.com:scylladb/scylladb:
test/perf/s3: Add --part-size-mb option for upload test
test/perf/s3: Add uploading test
test/perf/s3: Some renames not to be download-centric
test/perf/s3: Make object/file name configurable
test/perf/s3: Configure maximum number of sockets
test/perf/s3: Remove parallelizm
s3/client: Make http client connections limit configurable