S3 uploader: switch to aws-sdk-go-v2

[zmb3]

We have observed 503 errors in the auth uploader's CompleteMultipartUpload calls.

As per https://repost.aws/knowledge-center/http-5xx-errors-s3:

The error code 500 Internal Error indicates that Amazon S3 can't handle the request at that time. The error code 503 Slow Down typically indicates that the number of requests to your S3 bucket is high.

This same post says that:

All AWS SDKs have a built-in retry mechanism with an algorithm that uses exponential backoff.

However, it looks like there's a long-standing issue in aws-sdk-go where the SDK does not throttle S3 requests properly: aws/aws-sdk-go#3977

Edit: aws-sdk-go-v2 correctly implements throttled retries in this case. We should use it here.

[rosstimothy]

Does aws-sdk-go-v2 suffer from the same problem?

[zmb3]

Good thought, @rosstimothy.

No, it looks like aws-sdk-go-v2 does implement retries and throttling for this case: https://github.com/aws/aws-sdk-go-v2/blob/49b368e9d7a38a2373c833be135270e5390c2b41/aws/retry/standard.go#L72

V1 for reference: https://github.com/aws/aws-sdk-go/blob/53e4759915361d72a33be783d5e878a63d85f807/aws/request/retryer.go#L84-L96

[zmb3]

Closed by #44728