optimize ZK access in KafkaController

In KafkaController, we access ZK in the following places. Those accesses are not necessary since we can read from the cache in the controller.

In onBrokerFailure(deadBrokers: Seq[Int]),
replicaStateMachine.handleStateChanges(getAllReplicasOnBroker(zkClient, controllerContext.allTopics.toSeq, deadBrokers), OfflineReplica)
}

In onBrokerStartup(newBrokers: Seq[Int])
replicaStateMachine.handleStateChanges(getAllReplicasOnBroker(zkClient, controllerContext.allTopics.toSeq, newBrokers), OnlineReplica)
}

In shutdownBroker(),
getPartitionsAssignedToBroker(zkClient, controllerContext.allTopics.toSeq, id).map {
}