HDFS-17070. Remove unused import in DataNodeMetricHelper.java. (#5812). Contributed by farmmamba.

Reviewed-by: Xing Lin <linxingnku@gmail.com>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/metrics/DataNodeMetricHelper.java

@@ -17,7 +17,6 @@
  */
 package org.apache.hadoop.hdfs.server.datanode.metrics;
 
-import org.apache.hadoop.hdfs.server.datanode.metrics.FSDatasetMBean;
 import org.apache.hadoop.metrics2.MetricsCollector;
 import org.apache.hadoop.metrics2.MetricsTag;
 import org.apache.hadoop.metrics2.lib.Interns;