Fix EZP-22227: Solr tests are skipped

This PR resolves issue https://jira.ez.no/browse/EZP-22227

With recent lazy services changes SignalSlot Repository initialisation in Solr test factory was not updated.
That caused skipped integration tests when ran against Solr storage.

This changes skipping to failing, to ensure this does not happen again.
It also fixes SignalSlot Repository initialisation in Solr test factory.