fix(s3): Fix improper handle for copy response

[dentiny]

Which issue does this PR close?

Closes #7293

Rationale for this change

As described in the attached issue, currently we consider 200 OK HTTP status as copy success, but the doc also clarifies the error information could be contained in response body.

What changes are included in this PR?

In this PR, I make a few design decisions:

• If the response could be parsed to a valid CopyObjectResult (with ETag field present), then we consider it success
• Otherwise, it's considered as failure; I make it retriable because the copy request has been accepted at server side, it's copy operation failure, likely server internal error, resource exhausted, timeout, etc
  • Doc: If the error occurs before the copy action starts, you receive a standard Amazon S3 error.

Doc here: https://docs.aws.amazon.com/AmazonS3/latest/API/API_CopyObject.html

Are there any user-facing changes?

No

AI Usage Statement

No AI involvement.

[Xuanwo]

Thank you!