HDFS-16169. Fix TestBlockTokenWithDFSStriped#testEnd2End failure (#3850)

Reviewed-by: Fei Hui <feihui.ustc@gmail.com>
Reviewed-by: litao <tomleescut@gmail.com>
Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java

@@ -1687,6 +1687,11 @@ public class TestBalancer {
       BalancerParameters p = BalancerParameters.DEFAULT;
       runBalancer(conf, totalUsedSpace, totalCapacity, p, 0);
 
+      // namenode will ask datanode to delete replicas in heartbeat response
+      cluster.triggerHeartbeats();
+      // namenode will update block locations according to the report
+      cluster.triggerDeletionReports();
+
       // verify locations of striped blocks
       locatedBlocks = client.getBlockLocations(fileName, 0, fileLen);
       StripedFileTestUtil.verifyLocatedStripedBlocks(locatedBlocks, groupSize);