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# Type of request: This is a ...

[ X ] bug report
[ ] feature request

# Detailed description

On BatchWriteItem if items are throttled, we are expected to receive a list of `UnprocessedItems` in the response instead of HTTP 500

## Expected behavior

Receive HTTP 200 but with Unprocessed Items in the response: https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_BatchWriteItem.html#DDB-BatchWriteItem-response-UnprocessedItems

## Actual behavior

Receive HTTP 500 ProvisionedThroughPutException. "All or nothing"

# Steps to reproduce

Start LocalStack with DynamoDb Service and "DYNAMODB_ERROR_PROBABILITY=1.0"

## Command used to start LocalStack

```
new LocalStackContainer(DockerImageName.parse("localstack/localstack:0.12.9"))
      .withEnv("DYNAMODB_ERROR_PROBABILITY", "1.0")
      .withServices(DYNAMODB)
```

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

You can just Randomly generate a big list of objects (exceeding 1kb per batch) and check this behaviour


response.status_code = 200
            response._content = ''  
            fix_headers_for_updated_response(response)
            return response
        elif action == 'ListTagsOfResource':
            response = Response()
            response.status_code = 200
            response._content = json.dumps({
                'Tags': [
                    {'Key': k, 'Value': v}
                    for k, v in TABLE_TAGS.get(data['ResourceArn'], {}).items()
                ]
            })
            fix_headers_for_updated_response(response)
            return response
        elif action == 'EnableKinesisStreamingDestination':
            
            if not self.table_exists(ddb_client, data['TableName']):
                return get_table_not_found_error()
            stream = is_kinesis_stream_exists(stream_arn=data['StreamArn'])
            if not stream:
                return error_response(error_type='ValidationException',
                    message='User does not have a permission to use kinesis stream')
            return dynamodb_enable_kinesis_streaming_destination(data, table_def)
        elif action == 'DisableKinesisStreamingDestination':
            
            if not self.table_exists(ddb_client, data['TableName']):
                return get_table_not_found_error()
            stream = is_kinesis_stream_exists(stream_arn=data['StreamArn'])
            if not stream: