Since notify might not wake up the right thread, notifyAll should be used instead. (#6931)

* Since notify might not wake up the right thread, notifyAll should be used instead.

* Comment is added about why notifyAll() is not used.

extensions-contrib/druid-rocketmq/src/main/java/org/apache/druid/firehose/rocketmq/RocketMQFirehoseFactory.java

@@ -404,6 +404,7 @@ public class RocketMQFirehoseFactory implements FirehoseFactory<InputRowParser<B
         this.requestsWrite.add(request);
         if (!hasNotified) {
           hasNotified = true;
+          // No need to use notifyAll here since extended class com.alibaba.rocketmq.common.ServiceThread handles it
           notify();
         }
       }