[TASK] Fix PHPStan issues

Classes/Controller/Ajax/UploadController.php

Classes/Controller/BackendController.php

Classes/Controller/JobTeaserController.php

Classes/Controller/JoblistController.php

Classes/Domain/Model/Contact.php

Classes/Domain/Model/Job.php

Classes/Domain/Model/JobApplication.php

Classes/Domain/Repository/CompanyRepository.php

Classes/Domain/Repository/DepartmentRepository.php

Classes/Domain/Repository/ExperienceLevelRepository.php

Classes/Domain/Repository/JobRepository.php

Classes/Event/Listener/AccessPageListEventListener.php

Classes/Pagination/Pagination.php

Classes/Service/BackendService.php

Classes/Service/FileAndFolderService.php

Classes/Service/SitemapService.php

Classes/ViewHelpers/Backend/ControlViewHelper.php

Classes/ViewHelpers/Form/UploadViewHelper.php

Classes/ViewHelpers/Widget/UriViewHelper.php

ext_localconf.php