Fix risky tests without assertions

apps/dav/tests/unit/AppInfo/ApplicationTest.php

apps/dav/tests/unit/CalDAV/AbstractCalDavBackend.php

apps/dav/tests/unit/CalDAV/CalendarTest.php

...ests/unit/Connector/Sabre/CustomPropertiesBackendTest.php

apps/dav/tests/unit/Connector/Sabre/DirectoryTest.php

apps/dav/tests/unit/Connector/Sabre/FilesPluginTest.php

apps/encryption/tests/Hooks/UserHooksTest.php

apps/encryption/tests/RecoveryTest.php

..._external/tests/Service/UserGlobalStoragesServiceTest.php

apps/files_sharing/tests/ApiTest.php

apps/files_sharing/tests/External/ScannerTest.php

apps/files_sharing/tests/LockingTest.php

...es_sharing/tests/Middleware/OCSShareAPIMiddlewareTest.php

apps/files_trashbin/tests/BackgroundJob/ExpireTrashTest.php

apps/files_trashbin/tests/Command/ExpireTest.php

apps/files_trashbin/tests/StorageTest.php

apps/files_versions/tests/Command/ExpireTest.php

...isioning_api/tests/Controller/AppConfigControllerTest.php

apps/user_ldap/tests/LDAPProviderTest.php

apps/workflowengine/tests/Check/AbstractStringCheckTest.php