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 <span class="ref-name">fix/related_keys_test</span>
Status Job ID Name Coverage
  External
running ERP5.CodingStyleTest-Master

4583:05:48

running ERP5.UnitTest-Master.Medusa

4583:05:41