Use expense journal instead of expense account as payment clearing journal in scenario

(grafted from c8d00666ed773634be0dc970ba75631123c053bd)

--HG--
branch : 6.0

modules/account_payment_clearing/tests/scenario_account_payment_clearing.rst

@@ -60,7 +60,8 @@ Create payment journal::
 
     >>> PaymentJournal = Model.get('account.payment.journal')
     >>> payment_journal = PaymentJournal(name='Manual',
-    ...     process_method='manual', clearing_journal=expense,
+    ...     process_method='manual',
+    ...     clearing_journal=expense_journal,
     ...     clearing_account=bank_clearing,
     ...     clearing_posting_delay=datetime.timedelta(1))
     >>> payment_journal.save()