!49482 (merged) omitted the multipart upload URLs for Workhorse if the S3 client were used, but Rails doesn't actually control whether Workhorse will use the S3 client. For example, previously if Workhorse detected a blank region, it would not use the native client.
Since the multipart URLs were not available, Workhorse would attempt to
use the PutObject API for uploads, which might fail if chunked encodings
were used (e.g. by Maven or Conan).
We now always include these multipart URLs to be safe.