simulation: Add getTestedPropertyList() is still widely used so define it for compatibility sake.

Followup of: "simulation: improve equivalence testers explanations messages".

product/ERP5/mixin/equivalence_tester.py

@@ -230,3 +230,6 @@ class EquivalenceTesterMixin:
         if len(tested_property) == 1:
           setattr(self, 'tested_property', tested_property[0])
     return self._baseGetTestedProperty()
+
+  def getTestedPropertyList(self):
+    return [self.getTestedProperty()]