Show current event threshold in EVENT TRACKER POLICY SETTINGS

Developer cannot get crrent event threshold after changed app broadcast
/app bind service event tracker policy settings.
A reasonable approach is to dump current event threshold settings but 
not default event threshold.

Change-Id: I2e250a80b6cf5fa4e1d066c04d9c505a2db1ed9c

services/core/java/com/android/server/am/BaseAppStateTimeSlotEventsTracker.java

@@ -338,7 +338,7 @@ abstract class BaseAppStateTimeSlotEventsTracker
                 pw.print(prefix);
                 pw.print(mKeyNumOfEventsThreshold);
                 pw.print('=');
-                pw.println(mDefaultNumOfEventsThreshold);
+                pw.println(mNumOfEventsThreshold);
             }
             pw.print(prefix);
             pw.print("event_time_slot_size=");