MonitoringTopMenu: Prepend path to the top menu item

This is needed for PG UI to work properly.

Change-Id: Id317092ca5b665e91e8073ba6e16b6c985a258f1
(cherry picked from commit 7b3da0c594af0f628b44a18d338081a55b62e685)
diff --git a/src/main/java/com/googlesource/gerrit/plugins/javamelody/MonitoringTopMenu.java b/src/main/java/com/googlesource/gerrit/plugins/javamelody/MonitoringTopMenu.java
index 60ebf86..6e1b0a1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/javamelody/MonitoringTopMenu.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/javamelody/MonitoringTopMenu.java
@@ -29,7 +29,7 @@
     if (capabilityChecker.canMonitor()) {
       menuEntries.add(
           new MenuEntry(
-              "Monitoring", Collections.singletonList(new MenuItem("JavaMelody", "monitoring"))));
+              "Monitoring", Collections.singletonList(new MenuItem("JavaMelody", "/monitoring"))));
     }
   }