erp5_web_renderjs_ui_test: Restrict relation field match pattern.

Without this, more categories than can be displayed in the dropdown menu
may match, pushing expected "Quantity" one out of the list, causing the
test to fail.

bt5/erp5_web_renderjs_ui_test/PathTemplateItem/portal_tests/renderjs_ui_relation_field_zuite/testRelationFieldPercent.zpt

@@ -61,7 +61,7 @@
 </tr>
 <tr>
   <td>assertEval</td>
-  <td>(function() { selenium.browserbot.getCurrentWindow().document.getElementById("field_my_foo_category_title").value = "%"; return true;})()
+  <td>(function() { selenium.browserbot.getCurrentWindow().document.getElementById("field_my_foo_category_title").value = "Qua%"; return true;})()
   <td>true</td>
 </tr>
 <tr>