DrumSynth presets (.ds) export incorrectly, losing important information.

@sakertooth is already working on this.

Since Apr 22, 2025.

### System Information

Windows 10 (Huawei distribution), x86-64 (Intel CPU)

### LMMS Version(s)

1.2.2-stable (sorry, I'm not into nightly builds)

### Most Recent Working Version

_No response_

### Bug Summary

This bug is reproducible, the export works weird no matter the file format (.wav, .ogg, .mp3) is chosen, sample rate, bitrate doesn't matter at all. Simple project for reproduction and exported file are posted in zip-archive (because Github can't post .mmp files).
....
I am aware about https://github.com/LMMS/lmms/issues/6335, but original poster complains about difference _between_ versions, including the playback and export, I am complaining about difference between real-time sound and export itself on that one LMMS version. Please, feel the difference.

### Expected Behaviour

Have highest overtones to be heard and proper volume. My hearing is average, if not worse. I know there always will be a difference between "pure" real-time generated sound and baked one, but it shouldn't be **that** different.

### Steps To Reproduce

1.Open the project.
2. Listen the loop.
3.Export.
4.?????
5.PROFIT!!111

### Logs

Click to expand

### Screenshots / Minimum Reproducible Project

I know that's another export bug, but please, take it into consideration, because it would be a pity to write track with excessive usage of drumsynth and get bad export. A one of overcomings is to record audio with screen capture.

[export_test.zip](https://github.com/user-attachments/files/18876426/export_test.zip)

### Please search the issue tracker for existing bug reports before submitting your own.

- [x] I have searched all existing issues and confirmed that this is not a duplicate.