better s3 error and backtrace for storage-scrubber (and storage client)

[skyzh]

as part of the fix #8299, I added two things:

• Wrap S3 error with DisplayErrorContext to show the detailed error instead of simply status code.
• For retries, throw the original error instead of the wrapped anyhow error.

This should be applied to other places in the pageserver codebase so that we have a consistent error reporting message.

[arpad-m]

DisplayErrorContext is an S3 specific thing, does it work with Azure as well?

[skyzh]

It's an S3 SDK thing