Issue 6898 - Removed translations for 'add' strings from composer.json

Currently the Duplicate translations for "add" string in composer.json are causing warnings when trying to updated Dev. build, in order to prevent that warnings, we have to delete the duplications.

Add string from composer translation files are deleting using a manual script and all the empty files I removed manually, I think we are safe here, but having another eye on the changes would be great.

See also https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui/issues/175