MINOR: Rearrange configs in GroupCoordinatorConfigs (#18970)

I was looking into GroupCoordinatorConfigs to review configurations that
we will ship with Apache Kafka 4.0. I found out that it was pretty
disorganised. This patch cleans up the format and re-groups the
configurations which are related.

Reviewers: Chia-Ping Tsai <[email protected]>

Author: dajac