[bugfix][0.11]fix proxy decode bug

[Shirley125]

What this PR does / why we need it?

fix proxy decode bug while parsing non-UTF-8 characters.

Does this PR introduce any user-facing change?

How was this patch tested?

[github-actions]

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[gemini-code-assist]

Code Review

This pull request addresses a UnicodeDecodeError that can occur when decoding streamed chunks from backend servers. The change wraps the decode operation in a try...except block. In case of a decoding error, which can happen with split multi-byte characters, the raw byte chunk is yielded to the client. This prevents the proxy from crashing and is a correct approach for a streaming proxy, making the data forwarding more robust. The error handling is also consistent with how JSONDecodeError is handled elsewhere in the function. The changes in both modified files are identical and appropriate.