[PEx] Update cli default

Change each task to 2K schedules by default

Src/PRuntimes/PExRuntime/src/main/java/pex/commandline/PExConfig.java

@@ -71,7 +71,7 @@ public class PExConfig {
     ChoiceSelectorMode choiceSelectorMode = ChoiceSelectorMode.Random;
     // max number of schedules per search task
     @Setter
-    int maxSchedulesPerTask = 500;
+    int maxSchedulesPerTask = 2000;
     //max number of children search tasks
     @Setter
     int maxChildrenPerTask = 2;