Keys that may have lengths in the Animataion editor are not well displayed if the length is too short

### Tested versions

- Reproducible in: 4.3.stable, v4.4.dev3

### System information

Debian Linux/X11 12.7, xfwm4 4.18.0 with built-in compositor, AMD RX 550, Compatibility renderer

### Issue description

when animating the property ``AudioStreamPlayer:playing``, the checkboxes are only visible when the value is set to ``false``. if the value is ``true``, the checkbox is invisible — and it cannot be clicked: it must be drag‑selected

> 
> Animation panel showing an animation with the tracks ``AudioStreamPlayer:playing`` and ``ColorRect:visible`` being animated identically.
> the checkboxes on the ``ColorRect:visible`` track look and act normally,
> only the checkboxes on the ``AudioStreamPlayer:playing`` track are bugged

### Steps to reproduce

1. create a new Godot project
2. create a scene with an AnimationPlayer and an AudioStreamPlayer
3. add a sample to the AudioStreamPlayer
4. animate the proprety ``AudioStreamPlayer:playing`` using the AnimationPlayer

### Minimal reproduction project (MRP)

[2024-10-24_music-animation-bug.zip](https://github.com/user-attachments/files/17499031/2024-10-24_music-animation-bug.zip) (5.4 KiB before extracting and opening in Godot, 4.1 MiB after)

(credit: sample is located under ``shapes/micro.wav`` in [LMMS](https://lmms.io) built‑in samples)

Open the minimal reproduction project and reproduce the Animation panel issue with the AudioStreamPlayer:playing track, comparing it with ColorRect:visible. Trace the Animation editor UI responsible for drawing and hit-testing short key values; done means the checkbox is visible and clickable for both true and false values.

Written by the indexing model from the issue text.