* s3: abort a completed upload's leftover directory metadata-only
A .uploads/<id> directory can outlive the object it completed into when
the commit's metadata-only removal failed or the gateway died in between;
the restored part entries then share chunks with the published object.
AbortMultipartUpload deleted the directory recursively, chunks and all,
so aborting such a leftover destroyed a committed object (#11382).
Run the same check s3.clean.uploads gained in #11375 before deleting:
when the object entry or a version file under <key>.versions carries the
upload id, remove .uploads/<id> metadata-only and answer the abort; when
the lookup cannot decide, refuse with InternalError rather than risk
live chunks.
* s3: apply the completed-upload check to lifecycle MPU abort
lifecycleAbortMPU ran the same destructive recursive delete on
.uploads/<id>. Reuse uploadCompleted so a leftover whose object entry or
version file carries the upload id is removed metadata-only, and an
undecidable lookup retries later instead of freeing live chunks.
* s3: serialize abort's upload-dir delete with the object's commit
The completed check alone leaves a race: abort can read completed=false,
then an in-flight completion publishes the object over the same part
chunks before the recursive delete frees them.
Run the check and delete inside the object write lock, which non-routed
completions hold for their whole finalize. With an owner, send the data
delete as an ObjectTransaction on the object's lock key — a routed
commit then either loses its upload-exists precondition after our delete
or has already stamped the object, which the transaction's
IF_EXTENDED_NOT_EQUAL condition detects and falls back to a
metadata-only remove. lifecycleAbortMPU shares removeUploadDir so both
callers get the same ordering.
* s3: check for an empty object before resolving its write owner
* s3: check completion at the abort's resolved object key
An upload record missing ExtMultipartObjectKey skipped the completed
check entirely even though the request's Key names the object.
see https://blog.aqwari.net/xml-schema-go/
1. go get aqwari.net/xml/cmd/xsdgen
2. Add EncodingType element for ListBucketResult in AmazonS3.xsd
3. xsdgen -o s3api_xsd_generated.go -pkg s3api AmazonS3.xsd
4. Remove empty Grantee struct in s3api_xsd_generated.go
5. Remove xmlns: sed s'/http:\/\/s3.amazonaws.com\/doc\/2006-03-01\/\ //' s3api_xsd_generated.go