Retry throttles do not cap at 5 minutes

Retries for throttled request do not cap at 5 minutes due to [throttled boolean not being checked first](https://github.com/aws/aws-sdk-go-v2/blob/master/aws/default_retryer.go#L48-L52).

https://github.com/aws/aws-sdk-go/pull/1654