Fix test failure of destoryService()

Author: minggangw

test/test-extra-destroy-methods.js

@@ -93,7 +93,7 @@ describe('Node extra destroy methods testing', function () {
     const AddTwoInts = 'example_interfaces/srv/AddTwoInts';
     // const AddTwoInts = rclnodejs.require('example_interfaces/srv/AddTwoInts');
     var service = node.createService(AddTwoInts, 'add_two_ints', () => {});
-    assert.deepStrictEqual(node._services.length, 6);
+    assert.deepStrictEqual(node._services.length, 7);
 
     assertThrowsError(
       function () {