KAFKA-16226 Add test for concurrently updatingMetadata and fetching snapshot/cluster

[msn-tldr]

This is a follow-up to https://github.com/apache/kafka/pull/15323.

Metadata is typically updated concurrently in the background thread, and the MetadataSnapshot/Cluster are fetched & used in another thread(typically application thread). Make sure the concurrent update & read works as expected.

More detailed description of your change, if necessary. The PR title and PR message become the squashed commit message, so use a separate comment to ping reviewers.

Summary of testing strategy (including rationale) for the feature or bug fix. Unit and/or integration tests are expected for any behaviour change and system tests should be considered for larger changes.

Committer Checklist (excluded from commit message)

• [ ] Verify design and implementation
• [ ] Verify test coverage and CI build status
• [ ] Verify documentation (including upgrade notes)

[msn-tldr]

All the Jenkins test failures are in different tests, which are already known to have flaky history.