testERP5Catalog: test new related key syntaxes

In 4bcf5c6a (CatalogTool: Introduce new dynamic related key syntax, 2017-07-25)
we introduced a new syntax to solve some ambiguities in the previous syntax, but
the test suite was still testing the old syntax only.

Update tests to test the new syntax and to also check the old legacy syntax.
2 jobs for master
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

failed ERP5.UnitTest-Master.Medusa