remove outdated translation files

lib/private/l10n/ach.php

lib/private/l10n/af_ZA.php

lib/private/l10n/ar.php

lib/private/l10n/be.php

lib/private/l10n/bg_BG.php

lib/private/l10n/bn_BD.php

lib/private/l10n/bs.php

lib/private/l10n/ca.php

lib/private/l10n/cs_CZ.php

lib/private/l10n/cy_GB.php

lib/private/l10n/da.php

lib/private/l10n/de.php

lib/private/l10n/de_AT.php

lib/private/l10n/de_CH.php

lib/private/l10n/de_DE.php

lib/private/l10n/el.php

lib/private/l10n/en@pirate.php

lib/private/l10n/en_GB.php

lib/private/l10n/eo.php

lib/private/l10n/es.php