Hidden voices in parts should not play back

Issue type

Import/export issue

Bug description

If you create custom parts where you hide one or more of the voices, and then export the audio for those parts, they won't exclude the hidden voices.

This would seem to be a bug to me – the existing functionality is unlikely to be the desired outcome ever.

Steps to reproduce

1. Create a new score with one instrument
2. Add in some notes on voice 1 and voice 2
3. Create two parts in the parts dialog. Open both parts.
4. In the instruments panel, select Voices visible in the score and select voice 1.
5. Repeat previous step for the other part, and this time select voice 2.
6. Export audio (e.g. as MP3) and select all the parts.
7. Open up the exported files - and they will all be the same, no voices have been excluded in any of the audio files.

Screenshots/Screen recordings

https://github.com/musescore/MuseScore/assets/10707512/b279f81c-1405-451a-a51b-85899d19c56d

MuseScore Version

4.2.0-233521125

Regression

I don't know

Operating system

macOS 14.2

Additional context

OS: macOS 14.2, Arch.: x86_64, MuseScore version (64-bit): 4.2.0-233521125, revision: github-musescore-musescore-eb8d33c