Fixed EZP-21515: Missing Legacy Converter for UserMetaData Criterion

Issue: https://jira.ez.no/browse/EZP-21515

* [x] Remove the `CREATOR` criterion parameter which cannot be implemented in Legacy due to possible missing information (original content object creator = `ezcontentobject_version.creator_id WHERE ezcontentobject_version.version = '1'`): archived versions are removed over the time.
* [x] Add fixture data suitable for integration tests.
* [x] Create integration tests.