ERP5Type.Core.Folder: Fix recursive indexation of Trash Bins.

Since recent rework of isSubtreeIndexable, direct indexation of a trash bin
is fixed, but recursive indexation recursion condition broke: it stop just
above the trash bin instead of stopping just below it.

product/ERP5Type/Core/Folder.py

@@ -1251,8 +1251,10 @@ class Folder(CopyContainer, OFSFolder2, CMFBTreeFolder, CMFHBTreeFolder, Base, F
       )
 
   def _isDocumentNonIndexable(self, document):
-    return (getattr(aq_base(document), 'isSubtreeIndexable', None) is None
-            or not document.isSubtreeIndexable())
+    return (
+      getattr(aq_base(document), 'isAncestryIndexable', None) is None or
+      not document.isAncestryIndexable()
+    )
 
   def _updateActivateKwWithSerialisationTag(self, document, activate_kw):
     activate_kw['serialization_tag'] = document.getRootDocumentPath()