[IMP] survey: include the user's score in the notification email

The default email sent when a user succeed the certification will now
include the user's score. By opening the email, the users will directly
know how well they performed without having to log in.

task-2679881

Part-of: odoo/odoo#81057

addons/survey/data/mail_template_data.xml

@@ -71,7 +71,7 @@
                         <strong t-out="object.survey_id.display_name or ''">Furniture Creation</strong>
                     certification
                 </p>
-                <p>Congratulations for passing the test!</p>
+                <p>Congratulations for passing the test with a score of <strong t-out="object.scoring_percentage"/>% !</p>
             </td></tr>
         </tbody>
     </table>