[FIX] test_mail: increment the query counter for employee too

When searching the id mail.mail_activity_data_todo a request is done and
should be taken into account by the assertQueryCount.

This commit does just that... for the employee login.
Thanks to the murphy's law, the test branch was green.

addons/test_mail/tests/test_performance.py

@@ -133,7 +133,7 @@ class TestAdvMailPerformance(TransactionCase):
             'default_res_model': 'mail.test.activity',
         })
 
-        with self.assertQueryCount(admin=47, emp=51):
+        with self.assertQueryCount(admin=47, emp=52):
             model.create({
                 'summary': 'Test Activity',
                 'res_id': record.id,