feat(event): improve HistoryEventService unit test

Author: zeusoo001

framework/src/test/java/org/tron/core/event/HistoryEventServiceTest.java

@@ -80,6 +80,8 @@ public void test() throws Exception {
     Method method1 = historyEventService.getClass().getDeclaredMethod("syncEvent");
     method1.setAccessible(true);
     method1.invoke(historyEventService);
+
+    historyEventService.init();
     historyEventService.close();
   }
 }