fix a race condition in the perfschema.transaction_nested_events

mysql-test/suite/perfschema/include/transaction_nested_events_verifier.inc

@@ -13,7 +13,7 @@ let $wait_timeout= 10;
 let $wait_condition=
   SELECT COUNT(*) > 0 FROM performance_schema.threads
   WHERE THREAD_ID = @con1_thread_id
-    AND (PROCESSLIST_STATE = 'Sleep' OR PROCESSLIST_STATE IS NULL);
+    AND PROCESSLIST_COMMAND = 'Sleep';
 --source include/wait_condition.inc
 if(!$success)
 {