External storage tests require DB as well

apps/files_external/tests/backends/amazons3.php

apps/files_external/tests/backends/dropbox.php

apps/files_external/tests/backends/ftp.php

apps/files_external/tests/backends/google.php

apps/files_external/tests/backends/owncloud.php

apps/files_external/tests/backends/sftp.php

apps/files_external/tests/backends/sftp_key.php

apps/files_external/tests/backends/smb.php

apps/files_external/tests/backends/swift.php

apps/files_external/tests/backends/webdav.php