Is your feature request related to a problem? Please describe.
When I revisited the GroupMetadataManager related code, I found the code is not consistent with the latest Kafka implementation since it was written in a very early time.

Describe the solution you'd like
Follow the Kafka 3.0 source code to refactor the GroupMetadataManager to manage these two most important fields correctly:

  /* partitions of consumer groups that are being loaded, its lock should be always called BEFORE the group lock if needed */
  private val loadingPartitions: mutable.Set[Int] = mutable.Set()

  /* partitions of consumer groups that are assigned, using the same loading partition lock */
  private val ownedPartitions: mutable.Set[Int] = mutable.Set()