rpl.rpl_invoked_features fails sporadically with "Duplicate key error"

The reason was that Event e11 was re-executed before
"ALTER EVENT e11 DISABLE" had been executed.

Fixed by increasing re-schedule time

Other things:
- Removed double accounting of 'execution_count'. It was incremented in
  top->mark_last_executed(thd) that was executed a few lines earlier.

mysql-test/suite/rpl/r/rpl_invoked_features.result

@@ -45,14 +45,14 @@ BEGIN
 UPDATE t12 SET c = '';
 UPDATE t13 SET c = '';
 END|
-CREATE EVENT e1 ON SCHEDULE EVERY 1 SECOND DISABLE DO
+CREATE EVENT e1 ON SCHEDULE EVERY 10 SECOND DISABLE DO
 BEGIN
 ALTER EVENT e1 DISABLE;
 CALL p1(10, '');  
 END|
 Warnings:
 Warning	1105	Event scheduler is switched off, use SET GLOBAL event_scheduler=ON to enable it.
-CREATE EVENT e11 ON SCHEDULE EVERY 1 SECOND DISABLE DO
+CREATE EVENT e11 ON SCHEDULE EVERY 10 SECOND DISABLE DO
 BEGIN
 ALTER EVENT e11 DISABLE;
 CALL p11(10, '');  

mysql-test/suite/rpl/t/rpl_invoked_features.test

@@ -102,14 +102,17 @@ BEGIN
   UPDATE t13 SET c = '';
 END|
 
-# Create events which will run every 1 sec
+# Create events which will run every 10 sec
-CREATE EVENT e1 ON SCHEDULE EVERY 1 SECOND DISABLE DO
+# It cannot be much shorter as we have to ensure that a new
+# event is not scheduled before the DISABLE has been
+# executed.
+CREATE EVENT e1 ON SCHEDULE EVERY 10 SECOND DISABLE DO
 BEGIN
   ALTER EVENT e1 DISABLE;
   CALL p1(10, '');  
 END|
 
-CREATE EVENT e11 ON SCHEDULE EVERY 1 SECOND DISABLE DO
+CREATE EVENT e11 ON SCHEDULE EVERY 10 SECOND DISABLE DO
 BEGIN
   ALTER EVENT e11 DISABLE;
   CALL p11(10, '');  

sql/event_queue.cc

@@ -650,7 +650,6 @@ Event_queue::get_top_for_execution_if_time(THD *thd,
       top->status= Event_parse_data::DISABLED;
     DBUG_PRINT("info", ("event %s status is %d", top->name.str, top->status));
 
-    top->execution_count++;
     (*event_name)->dropped= top->dropped;
     /*
       Save new values of last_executed timestamp and event status on stack