Remove the config datafusion.execution.coalesce_target_batch_size and use datafusion.execution.batch_size instead

[yahoNanJing]

Which issue does this PR close?

Closes #4756.

Rationale for this change

As #4756 mentioned, 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.

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[yahoNanJing]

Hi @alamb, @andygrove, could you help review this PR?

[alamb]

I think this change makes a lot of sense. Thank you @yahoNanJing

Maybe @Dandandan remembers why there were two different batch sizes

[alamb]

That reads much more nicely 👍

[alamb]

I plan to merge this later today unless there are any more comments.

[yahoNanJing]

Since there's no opposite comments, I will merge this PR.

[ursabot]

Benchmark runs are scheduled for baseline = ac876db and contender = f7477dc. f7477dc is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java