Metronome is sending as regular note all the time via MIDI Out device

** Description**
In Mu4 metronome is configured as a regular instrument. But due to using Midi channel 1 and note midi events it is sent via Midi output as a regular midi notes. Metronome should have own midi channel to be independent.
Also reproducible when MuseScore is opened at the same time with Guitar pro (with opened tab)

To Reproduce
Steps to reproduce the behavior:

1. Create new empty score
2. Select Midi output to your device (audio interface, synth etc.)
3. Play the score
4. Pay attention to the A3 sounding all the time as a metronome

Expected behavior
To be discussed

Platform information

• OS: [e.g. macOS, Windows, Linux]