Expose AdminClient exception when failing to describe the cluster

[harmadasg]

If the AdminClient fails to describe the cluster, the exception is not exposed.

 2024-09-23 20:03:28,871 ERROR com.linkedin.kafka.cruisecontrol.KafkaCruiseControlMain: [main]: Uncaught exception on thread Thread[main,5,main]
java.lang.RuntimeException: Failed to describe Kafka cluster configs.
        at com.linkedin.kafka.cruisecontrol.config.KafkaAdminTopicConfigProvider.configure(KafkaAdminTopicConfigProvider.java:174) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.config.KafkaCruiseControlConfigUtils.getConfiguredInstance(KafkaCruiseControlConfigUtils.java:49) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.config.KafkaCruiseControlConfig.getConfiguredInstance(KafkaCruiseControlConfig.java:98) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.monitor.LoadMonitor.<init>(LoadMonitor.java:155) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.monitor.LoadMonitor.<init>(LoadMonitor.java:124) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.KafkaCruiseControl.<init>(KafkaCruiseControl.java:126) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.async.AsyncKafkaCruiseControl.<init>(AsyncKafkaCruiseControl.java:34) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.KafkaCruiseControlApp.<init>(KafkaCruiseControlApp.java:36) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.KafkaCruiseControlServletApp.<init>(KafkaCruiseControlServletApp.java:32) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.KafkaCruiseControlUtils.getCruiseControlApp(KafkaCruiseControlUtils.java:923) ~[cruise-control-2.5.116.jar:?]
        at com.linkedin.kafka.cruisecontrol.KafkaCruiseControlMain.main(KafkaCruiseControlMain.java:37) ~[cruise-control-2.5.116.jar:?]

The reason is that the exception generated by AdminClient is caught and a generic RuntimeException is thrown in KafkaAdminTopicConfigProvider but the original error trace is lost. This PR adds the original exception as the cause of the newly thrown RuntimeException. This change can improve troubleshooting and makes it much easier to figure out what went wrong with the DESCRIBE_CLUSTER API call.

[viktorsomogyi]

@mhratson would you please review this small PR?