Return 400 for botocore client errors

[yunfeng-scale]

Pull Request Summary

Return 400 for some client errors

Test Plan and Usage Guide

tested calling an endpoint with long message and received:
<Response [400]>

{"detail":"Invalid request: Error sending celery task: An error occurred (InvalidParameterValue) when calling the SendMessage operation: One or more parameters are invalid. Reason: Message must be shorter than 262144 bytes."}

[edgan8]

Is there a more specific error we can catch so we don't inadvertently classify internal bugs as 400s?

[yunfeng-scale]

yes i can check the error message whether it's about message size. but for now i want to make it simple and count every boto client error as user errors :) we can revisit it later when users complain.