MINOR: Collect metadata log dir in kraft system tests (#12215)
MINOR: Collect metadata log dir in kraft system tests (#12215)

It is useful to collect the directory for `__cluster_metadata` in system tests. We use a separate directory from user partitions, so it must be configured separately. 

Reviewers: David Arthur <cf0ebc4830a5411dc7b6b71d0c325c88bc925cca@gmail.com>
lindong28/kafka,apache/kafka,apache/kafka,guozhangwang/kafka,apache/kafka,apache/kafka,lindong28/kafka,lindong28/kafka,lindong28/kafka,guozhangwang/kafka,guozhangwang/kafka,guozhangwang/kafka