Support Kafka's ProducerConfig.REQUEST_TIMEOUT_MS_CONFIG.

[MarvinCai]

Motivatio
Support Kafka's ProducerConfig.REQUEST_TIMEOUT_MS_CONFIG #1090

Previously ProducerBuilder.sendTimeout was set by parsing Kafka's ProducerConfig.MAX_BLOCK_MS_CONFIG.
According to Kafka's document it's for

Controlling how long KafkaProducer.send() and KafkaProducer.partitionsFor() will block either because the buffer is full or metadata unavailable.

But ProducerBuilder.sendTimeout is for

If a message is not acknowledged by the server before the sendTimeout expires, an error will be reported.

And Kafka's ProducerConfig.REQUEST_TIMEOUT_MS_CONFIG, according to the document is for:

Controlling the maximum amount of time the client will wait for the response of a request.

Which I think would be better fit purpose of Pulsar's ProducerBuilder.sendTimeout.

[sijie]

@MarvinCai

Nice catch!

[sijie]

run integration tests
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[sijie]

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