Synchronize AFP Amplify knob and Graph when sample file changed

### System Information

Windows

### LMMS Version(s)

nightly

### Most Recent Working Version

-

### Bug Summary

When you drop in a new sample over Audio File Processor (with modified amplify settings), the Amplify knob rests in previous state. And, the sample loads normally (sample graph is set to no amplified state).

### Expected Behaviour

1. Either the newly dropped in sample should be set to no amplification state,
2. Or, the sample's graph should update to old amplification status.

### Steps To Reproduce

Open AFP.
Drop a sample, eg. any drumsynth file.
Watch for amplification knob, and modify it, eg,. set it to full amplification.
Now, replace with a new sample over this instance of AFP.
Monitor amplification knob settings and sample's graph.

Try to adjust the amplify knob. Graph changes immediately.

### Logs

_No response_

### Screenshots / Minimum Reproducible Project

_No response_

### 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.

Start with the Audio File Processor (AFP) and reproduce the behavior by changing the amplify setting, then replacing the sample. Trace how the amplify knob and sample graph are updated on sample replacement. Done means the newly loaded sample and the displayed amplification state remain synchronized.

Written by the indexing model from the issue text.