fix: emit all errors to get total # of errors

[chungjac]

Problem

• Previously, error metrics were only emitted when the backend returned a status code. However, mid-stream exceptions, which we now log the request IDs, lack status codes, causing these error metrics to not be emitted

Solution

• Extended error metric emission to include cases without status codes For unactionable errors, such as user-dependent errors like PromptCharacterLimit, we will emit a custom message so we can query in kibana. This ensures we capture all relevant error states for monitoring and debugging.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.