Replaced deprecated Kafka client poll with the recommended one

Author: jzakaryan

datastream-kafka-connector/src/main/java/com/linkedin/datastream/connectors/kafka/AbstractKafkaBasedConnectorTask.java

@@ -508,7 +508,7 @@ protected void trackEventsProcessedProgress(int recordCount) {
   }
 
   protected ConsumerRecords<?, ?> consumerPoll(long pollInterval) {
-    return _consumer.poll(pollInterval);
+    return _consumer.poll(Duration.ofMillis(pollInterval));
   }
 
   /**

datastream-kafka-connector/src/main/java/com/linkedin/datastream/connectors/kafka/mirrormaker/KafkaMirrorMakerConnectorTask.java

@@ -424,7 +424,7 @@ protected void maybeCommitOffsets(Consumer<?, ?> consumer, boolean hardCommit) {
       // Kafka rejects a poll if there is empty assignment
       return ConsumerRecords.EMPTY;
     } else {
-      return _consumer.poll(pollInterval);
+      return _consumer.poll(Duration.ofMillis(pollInterval));
     }
   }