Add timeout on TestDefaultLoadBalancer#testBalancerCluster to see if we can stop it hanging as a zombie in precommit builds

hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/TestDefaultLoadBalancer.java

@@ -108,7 +108,7 @@ public class TestDefaultLoadBalancer extends BalancerTestBase {
    *
    * @throws Exception
    */
-  @Test
+  @Test (timeout=60000)
   public void testBalanceCluster() throws Exception {
 
     for (int[] mockCluster : clusterStateMocks) {