Addendum for HDFS-10534: revert accidental change to MiniHadoopClusterManager.java.

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/mapreduce/MiniHadoopClusterManager.java

@@ -252,7 +252,7 @@ public class MiniHadoopClusterManager {
 
     // HDFS
     noDFS = cli.hasOption("nodfs");
-    numDataNodes = intArgument(cli, "datanodes", 100);
+    numDataNodes = intArgument(cli, "datanodes", 1);
     nnPort = intArgument(cli, "nnport", 0);
     dfsOpts = cli.hasOption("format") ? StartupOption.FORMAT
         : StartupOption.REGULAR;