rgw: aws-chunked need not supply any content-length

rgw: aws-chunked need not supply any content-length

The updated logic for aws chunked handling (2024) appears sufficient
to handle the cases produced by aws-sdk-go-v2.

Note that https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming.html
states that "For all requests, you must include the
x-amz-decoded-content-length header, specifying the size of the object in
bytes." (accessed 5/17/2025) (but now we do not enforce it).

Reported (with reproducer!) by: Fred Heinecke.

Fixes: https://tracker.ceph.com/issues/71183
Signed-off-by: Matt Benjamin <mbenjamin@redhat.com>