EZP-21765: Fix number of parameters to match parent

When running the eZ Find Unit Test Suite, errors are thrown because `getClassAttributeType()` and `getFieldName()` don't match their parents in `ezfSolrDocumentFieldDummyExample`.

This PR fixes that.

https://jira.ez.no/browse/EZP-21765

Cheers
:octocat: Jérôme