ERP5Type: don't set portal_type on instance

It's enough to set on the class and if we don't have it on instances, it
saves a few bytes in pickles

bt5/erp5_core_test/TestTemplateItem/portal_components/test.erp5.testZODBHistory.py

@@ -84,7 +84,6 @@ class TestZODBHistory(ERP5TypeTestCase):
     self.assertTrue(len(history_list) > 0)
     d = history_list[0]
     changes = d['changes']
-    self.assertEqual(changes['portal_type'], 'Organisation')
     self.assertEqual(changes['id'], 'org')
     self.assertTrue(changes['uid'] is not None)
 

product/ERP5Type/ERP5Type.py

@@ -399,6 +399,7 @@ class ERP5TypeInformation(XMLObject,
           self.getId(),
           temp=temp_object)
       base_ob = klass(id)
+      assert base_ob.portal_type == self.getId()
       ob = base_ob.__of__(container)
 
       if temp_object:
@@ -422,10 +423,6 @@ class ERP5TypeInformation(XMLObject,
         if getattr(base_ob, 'uid', None) is None:
           ob.uid = portal.portal_catalog.newUid()
 
-      # Portal type has to be set before setting other attributes
-      # in order to initialize aq_dynamic
-      ob.portal_type = self.getId()
-
       if compute_local_role:
         # Do not reindex object because it's already done by manage_afterAdd
         self.updateLocalRolesOnDocument(ob, reindex=False)