Remove the config `datafusion.execution.coalesce_target_batch_size`

[yahoNanJing]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

There's already a config of datafusion.execution.batch_size to indicate the row number of a batch for processing. I don't think it's necessary to make a different batch size for the CoalesceBatches rule.

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