These files are currently not being used nor compiled in MariaDB. The
use of large lists of 'case' statements in these source files are also
not a great way to represent translated strings. This git history can
be referred to when a better translation interface can be implemented
in the future.

Therefore, these files can be removed to cleanup the MariaDB codebase.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.