Change loglevel of cancelled errors to info

[Laityned]

See #1583

When closing the connection on purpose by calling consumer.close(), each ongoing Fetch request will be cancelled, by setting a Cancelled KafkaException on that particular request.

Due to the error callback on this object, which is nothing else except a logging statement, the cancellation will be logged with level ERROR, instead as INFO, while it is not actually an error, but a way of stopping the ongoing request

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This change is 

[Laityned]

bump @wbarnha

[dpkp]

Merged in #2467