Accounting/Payment Mean: fix the way relationship to PTG is reset on copy & paste

The previous way was duplicating transaction references since
AccountingTransaction_afterClone was no longer called.

bt5/erp5_accounting/SkinTemplateItem/portal_skins/erp5_accounting/AccountingTransactionLine_afterClone.xml

@@ -59,6 +59,7 @@ context.setGroupingReference(None)\n
 context.setGroupingDate(None)\n
 \n
 context.setAggregate(None, portal_type=\'Bank Reconciliation\')\n
+context.setAggregate(None, portal_type=\'Payment Transaction Group\')\n
 
 
 ]]></string> </value>

bt5/erp5_payment_mean/SkinTemplateItem/portal_skins/erp5_payment_mean/PaymentTransaction_afterClone.xml

-<?xml version="1.0"?>
-<ZopeData>
-  <record id="1" aka="AAAAAAAAAAE=">
-    <pickle>
-      <global name="PythonScript" module="Products.PythonScripts.PythonScript"/>
-    </pickle>
-    <pickle>
-      <dictionary>
-        <item>
-            <key> <string>Script_magic</string> </key>
-            <value> <int>3</int> </value>
-        </item>
-        <item>
-            <key> <string>_bind_names</string> </key>
-            <value>
-              <object>
-                <klass>
-                  <global name="NameAssignments" module="Shared.DC.Scripts.Bindings"/>
-                </klass>
-                <tuple/>
-                <state>
-                  <dictionary>
-                    <item>
-                        <key> <string>_asgns</string> </key>
-                        <value>
-                          <dictionary>
-                            <item>
-                                <key> <string>name_container</string> </key>
-                                <value> <string>container</string> </value>
-                            </item>
-                            <item>
-                                <key> <string>name_context</string> </key>
-                                <value> <string>context</string> </value>
-                            </item>
-                            <item>
-                                <key> <string>name_m_self</string> </key>
-                                <value> <string>script</string> </value>
-                            </item>
-                            <item>
-                                <key> <string>name_subpath</string> </key>
-                                <value> <string>traverse_subpath</string> </value>
-                            </item>
-                          </dictionary>
-                        </value>
-                    </item>
-                  </dictionary>
-                </state>
-              </object>
-            </value>
-        </item>
-        <item>
-            <key> <string>_body</string> </key>
-            <value> <string># aggregate link to a Payment Transaction Group should b reset on the child\n
-# accounting lines when a Payment Transaction is cloned.\n
-for line in context.getMovementList(\n
-        portal_type=context.getPortalAccountingMovementTypeList()):\n
-  line.setAggregate(None)\n
-</string> </value>
-        </item>
-        <item>
-            <key> <string>_params</string> </key>
-            <value> <string></string> </value>
-        </item>
-        <item>
-            <key> <string>id</string> </key>
-            <value> <string>PaymentTransaction_afterClone</string> </value>
-        </item>
-      </dictionary>
-    </pickle>
-  </record>
-</ZopeData>