fix team chat beep sound

There are two beep sounds :

• General chat and (talk.wav)
• team messages (talk2.wav)

These should not be converted to ogg, otherwise the engine does not find talk2.wav.

See: https://gitlab.com/xonotic/darkplaces/blob/div0-stable/cl_parse.c#L517

This causes that the beep sound for general chat is used for team messages, too.

The script cached_converter.sh already tries excludes them (But uses wrong path.)