Create and reuse kafka client where possible (#177)

* Create and reuse kafka client where possible

* Code cleanup

* fix code style violation

Author: Crim

kafka-webview-ui/src/main/java/org/sourcelab/kafka/webview/ui/manager/kafka/KafkaConsumerFactory.java

@@ -68,6 +68,7 @@ public KafkaConsumer createConsumer(final ClientConfig clientConfig) {
     /**
      * Create a new KafkaConsumer based on the passed in ClientConfig, and subscribe to the appropriate
      * partitions.
+     * @deprecated To be removed.
      */
     public KafkaConsumer createConsumerAndSubscribe(final ClientConfig clientConfig) {
         final KafkaConsumer kafkaConsumer = createConsumer(clientConfig);