[Bug] - REST CompleteMultipartUpload - InvalidPart error doesn't include diagnostic parameters

[lrm25]

Describe the bug
A direct-to-s3 call to CompleteMultipartUpload with an invalid part returns a response like this:

<Error>
  <Code>InvalidPart</Code>
  <Message>One or more of the specified parts could not be found.  The part may not have been uploaded, or the specified entity tag may not match the part's entity tag.</Message>
  <UploadId>woSP7MRqUOq6DDakmxl9eIWurOAp9PVyTXrZ0plUmSpHtni5nZBRuGl6fMRHh53BUwzAhF.T7EoYxOAqhNzA7KnruGbiSvSbfsymFlJom95qHDO4Q3hPQFWFxKANi87N</UploadId>
  <PartNumber>1</PartNumber>
  <ETag>gibberish</ETag>
  <RequestId>HKCGS5PTX4HGSMP9</RequestId>
  <HostId>DhvkCqhi6vyd8giple6BIxVEAqSycOK7qUoqTRv9kUt4CZArqZrfFYANFIjsv/QZxnXVCaQUKtY=</HostId>
</Error>

The versitygw response doesn't include the UploadId, PartNumber, or ETag.

To Reproduce

1. Start versitygw, e.g.: ./versitygw --access=AKIA**** --secret=******** --region=us-east-1 --iam-dir=/Users/lukemccrone/devel/versitygw/iam --cert /Users/lukemccrone/devel/versitygw/cert.pem --key /Users/lukemccrone/devel/versitygw/versitygw.pem posix --versioning-dir /tmp/versioning /tmp/gw
2. Create a bucket, e.g.: aws --no-verify-ssl s3api create-bucket --bucket versity-gwtest-bucket-one-1
3. Create a large file, and split into 4 parts.
4. Upload each part to the bucket, e.g.: aws --no-verify-ssl s3api put-object --body /Users/lukemccrone/devel/versitygw/versity-gwtest-files/test_file-0 --bucket versity-gwtest-bucket-one-1 --key test_file-0 for each part.
5. Create multipart upload with REST script, e.g.: curl -ks -w %{http_code} -X POST https://localhost:7070/versity-gwtest-bucket-one-1/test_file?uploads= -H Authorization: AWS4-HMAC-SHA256 Credential=********/20241230/us-east-1/s3/aws4_request,SignedHeaders=host;x-amz-content-sha256;x-amz-date,Signature=a1d2efbea7f887a54ef66138f2b5924d118db5e6ba82f7e4d763f32a458071c8 -H x-amz-content-sha256: UNSIGNED-PAYLOAD -H x-amz-date: 20241230T170902Z -o /Users/lukemccrone/devel/versitygw/versity-gwtest-files/output.txt
6. Run UploadPartCopy with upload_part_copy.sh script, e.g.: curl -ks -w %{http_code} -X PUT https://localhost:7070/versity-gwtest-bucket-one-1/test_file?partNumber=1&uploadId=a14dcaa0-8005-4ed5-8635-9f53d21a24a5 -H Authorization: AWS4-HMAC-SHA256 Credential=********/20241230/us-east-1/s3/aws4_request,SignedHeaders=host;x-amz-content-sha256;x-amz-copy-source;x-amz-date,Signature=6eaad4416632bcb559c392b53ff1bec07742ad75fb50f60c5c0c3fd618bef5cb -H x-amz-content-sha256: UNSIGNED-PAYLOAD -H x-amz-copy-source: versity-gwtest-bucket-one-1/test_file-0 -H x-amz-date: 20241230T170902Z -o /Users/lukemccrone/devel/versitygw/versity-gwtest-files/response.txt for each part.
7. Attempt to complete upload with inaccurate ETag, e.g.: curl -ks -w %{http_code} -X POST https://localhost:7070/versity-gwtest-bucket-one-1/test_file?uploadId=a14dcaa0-8005-4ed5-8635-9f53d21a24a5 -H Authorization: AWS4-HMAC-SHA256 Credential=********/20241230/us-east-1/s3/aws4_request,SignedHeaders=host;x-amz-content-sha256;x-amz-date,Signature=01bda6b17fc5c6b3c6d873de87e7cb6205e7b966024b2351f76be0b91bfd8937 -H x-amz-content-sha256: 5d5039c11d235c65c32999adf7a3e63242979e04722af1e3ffa54e6f49d45a31 -H x-amz-date: 20241230T170903Z -H Content-Type: application/xml -d <CompleteMultipartUpload xmlns="http://s3.amazonaws.com/doc/2006-03-01/"><Part><ETag>gibberish</ETag><PartNumber>1</PartNumber></Part><Part><ETag>gibberish</ETag><PartNumber>2</PartNumber></Part><Part><ETag>gibberish</ETag><PartNumber>3</PartNumber></Part><Part><ETag>gibberish</ETag><PartNumber>4</PartNumber></Part></CompleteMultipartUpload> -o /Users/lukemccrone/devel/versitygw/versity-gwtest-files/result.txt

Expected behavior
As with direct, UploadId, PartNumber, and ETag are shown.

Server Version
Version : v1.0.9
Build : bf20fa7
BuildTime: 2024-12-26_03:50:17PM
Darwin Lukes-MacBook-Pro.local 23.4.0 Darwin Kernel Version 23.4.0: Fri Mar 15 00:12:25 PDT 2024; root:xnu-10063.101.17~1/RELEASE_ARM64_T6030 arm64