aws/request: Add RequestThrottledException to set of throttled exceptions (#2496)
aws/request: Add RequestThrottledException to set of throttled exceptions (#2496)

Adds RequestThrottledException to the set of the SDK's throttled exceptions to retry and rate limit.
yxd-hde/aws-sdk-go,jasdel/aws-sdk-go,yxd-hde/aws-sdk-go,yxd-hde/aws-sdk-go,aws/aws-sdk-go,yxd-hde/aws-sdk-go