PartitionKeys in Metadata for KinesisAnalyticsInputPreprocessingResponse.Record missing

[tonyjayfunk]

This is used for Dynamic Partitioning, seemingly required as per https://docs.aws.amazon.com/firehose/latest/dev/dynamic-partitioning-partitioning-keys.html