[FIX] rating_project: hide rating in thread

Hide rating in issue history, otherwise the user can use the link
himself to change the rating.

opw-692598

addons/rating_project/data/project_data.xml

@@ -53,7 +53,7 @@
                 <p>We appreciate your feedback. It helps us to improve continuously.</p>
             </td></tr>
             <tr><td style="padding:10px 20px">
-                <table style="width:100%;border-top:1px solid #e1e1e1;">
+                <table summary="o_mail_notification" style="width:100%;border-top:1px solid #e1e1e1;">
                     <tr>
                         <td style="text-align:center;">
                             <h2 style="font-weight:300;font-size:18px;">