Set upper limit to 72

Author: prwhelan

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java

@@ -765,6 +765,7 @@ public void loadExtensions(ExtensionLoader loader) {
         "xpack.ml.trained_models.adaptive_allocations.scale_to_zero_time",
         TimeValue.timeValueHours(4),
         TimeValue.timeValueMinutes(1),
+        TimeValue.timeValueHours(72),
         Property.Dynamic,
         Setting.Property.NodeScope
     );