provider/aws: Handle LimitExceededException for subscriber limits
- Updates aws-sdk-go/request for retryer fix
- Fixes dynamoDB exception handling to catch subscriber limit error
When the `aws-sdk-go` dep releases the next release, we can tag the vendor with the new
release version, and merge this. Until then, soft-updated the vendor solely for the `request` package to post fix.
DynamoDB Fix:
```
aws_dynamodb_table.bar: Creating...
arn: "" => "<computed>"
attribute.#: "" => "1"
attribute.4228504427.name: "" => "id"
attribute.4228504427.type: "" => "S"
hash_key: "" => "id"
name: "" => "over-cap-test"
read_capacity: "" => "5"
stream_arn: "" => "<computed>"
stream_enabled: "" => "<computed>"
stream_view_type: "" => "<computed>"
write_capacity: "" => "5"
Error applying plan:
1 error(s) occurred:
* aws_dynamodb_table.bar: 1 error(s) occurred:
* aws_dynamodb_table.bar: AWS Error creating DynamoDB table: LimitExceededException: Subscriber limit exceeded: There is a limit of 256 tables per subscriber
status code: 400, request id: J2MC7MR060VKBPHP9P6JG5B6Q3VV4KQNSO5AEMVJF66Q9ASUAAJG
```
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