Disallow users to configure `max.in.flight.requests.per.connection` bigger than 5

As idempotent producer is the default behavior in 4.0, we should add a upper bound (5) to `max.in.flight.requests.per.connection`.

reference:

[0] https://github.com/apache/kafka/pull/11788#discussion_r810402844
[1] https://github.com/apache/kafka/blob/af53758746485daa06c4d4366036c04f7f9f0e63/clients/src/main/java/org/apache/kafka/clients/producer/ProducerConfig.java#L589