Enhance test_tales_expression field

Proxify it against my_view_mode_tales_expression (It use External Validator to check  Tales expression Syntax)

remove default tales expression of field because assertion that a TALES expression starts always with "python:" is wrong.

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/Predicate_view/my_test_tales_expression.xml

@@ -10,7 +10,6 @@
             <key> <string>delegated_list</string> </key>
             <value>
               <list>
-                <string>default</string>
                 <string>title</string>
               </list>
             </value>
@@ -53,12 +52,6 @@
             <key> <string>tales</string> </key>
             <value>
               <dictionary>
-                <item>
-                    <key> <string>default</string> </key>
-                    <value>
-                      <persistent> <string encoding="base64">AAAAAAAAAAI=</string> </persistent>
-                    </value>
-                </item>
                 <item>
                     <key> <string>field_id</string> </key>
                     <value> <string></string> </value>
@@ -71,10 +64,6 @@
                     <key> <string>target</string> </key>
                     <value> <string></string> </value>
                 </item>
-                <item>
-                    <key> <string>title</string> </key>
-                    <value> <string></string> </value>
-                </item>
               </dictionary>
             </value>
         </item>
@@ -82,13 +71,9 @@
             <key> <string>values</string> </key>
             <value>
               <dictionary>
-                <item>
-                    <key> <string>default</string> </key>
-                    <value> <string></string> </value>
-                </item>
                 <item>
                     <key> <string>field_id</string> </key>
-                    <value> <string>my_string_field</string> </value>
+                    <value> <string>my_view_mode_tales_expression</string> </value>
                 </item>
                 <item>
                     <key> <string>form_id</string> </key>
@@ -108,17 +93,4 @@
       </dictionary>
     </pickle>
   </record>
-  <record id="2" aka="AAAAAAAAAAI=">
-    <pickle>
-      <global name="TALESMethod" module="Products.Formulator.TALESField"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>_text</string> </key>
-            <value> <string>python: [\'python: True\',here.getTestTalesExpression()][str(here.getTestTalesExpression()).startswith(\'python\')]</string> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
 </ZopeData>

product/ERP5/bootstrap/erp5_core/bt/revision

-40954
+40955
\ No newline at end of file