erp5_property_sheets: remove an unsued mistakenly added property from Base property sheets.

product/ERP5/bootstrap/erp5_property_sheets/PropertySheetTemplateItem/portal_property_sheets/Base/ref_property.xml

-<?xml version="1.0"?>
-<ZopeData>
-  <record id="1" aka="AAAAAAAAAAE=">
-    <pickle>
-      <global name="Standard Property" module="erp5.portal_type"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>categories</string> </key>
-            <value>
-              <tuple>
-                <string>elementary_type/string</string>
-              </tuple>
-            </value>
-        </item>
-        <item>
-            <key> <string>description</string> </key>
-            <value> <string>Reference for accessor and method generation. It\'s design for ERP5 Workflow project in 2015. \n
-To replace the role of "id" in this case.\n
-Not necessary for other objects.</string> </value>
-        </item>
-        <item>
-            <key> <string>id</string> </key>
-            <value> <string>ref_property</string> </value>
-        </item>
-        <item>
-            <key> <string>portal_type</string> </key>
-            <value> <string>Standard Property</string> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-</ZopeData>