HDFS-13927. Addendum: Improve TestDataNodeMultipleRegistrations#testDNWithInvalidStorageWithHA wait. Contributed by Ayush Saxena.

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeMultipleRegistrations.java

@@ -310,7 +310,7 @@ public class TestDataNodeMultipleRegistrations {
           }
           return true;
         }
-      }, 500, 10000);
+      }, 500, 20000);
     } finally {
       cluster.shutdown();
     }