As detailed in te upstream issue Migrate off internal Kafka APIs to Improve Compatibility and Maintainability #2282, the existing Cruise Control tests rely on the Kafka server wrapper class, CCEmbeddedBroker, which uses several non-public Kafka APIs. These internal APIs lack stability and compatibility guarantees, making it increasingly difficult to upgrade Kafka versions.

This task is to migrate the `CruiseControlMetricsReporterTest` tests to use TestContainers to replace its usage of the CCEmbeddedBroker  class and thus remove its dependence on private Kafka APIs and make it easier to test against different Kafka versions.