Fix EZP-21958: Increase code coverage for EzPublishCoreBundle config parsers

https://jira.ez.no/browse/EZP-21958

## TODO

* [x] Common
* [ ] Content
* [ ] BlockView
* [ ] [Content|Location]View
* [ ] FieldDefinitionSettingsTemplates
* [ ] FieldTemplates
* [ ] Page
* [ ] Templates