Backspace key only deletes one note in Note-input mode

Issue type

Other type of issue

Bug description

In MuseScore 4.0.2, only the last note entered can be deleted no matter how many times the Backspace key is pressed in Note-input mode. The user will have to exit Note-input mode to select-delete the unwanted notes or press Ctrl+Z instead, making the same process more awkward and time-consuming. I would expect the Backspace key in MuseScore 4.x to behave similarly in Note-input mode as it does in MuseScore 3.x.

(See the screen recording below for comparison.)

Steps to reproduce

1. Create a new score.
2. Press 'N' to switch to note input mode.
3. Type letter keys to enter some notes.
4. Press Backspace multiple times.

Expected behavior: Each press of the backspace key should result in a note being deleted.
Actual behavior: Only the first press of backspace results in a note being deleted.

Screenshots/Screen recordings

https://github.com/musescore/MuseScore/assets/70313425/0463e37c-9210-4988-955d-6ca5bb2320c2

MuseScore Version

4.0.2

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

Windows 10

Additional context

No response

Reproduce the issue in MuseScore 4.0.2 by creating a score, entering Note-input mode with N, adding several notes, and pressing Backspace repeatedly. Trace the Note-input Backspace handling and compare its behavior with MuseScore 3.x; done means each press removes the preceding note without leaving Note-input mode.