Remove Node2D scale handler warning and image from the physics introduction

**Your Godot version:**
Godot 4.0 RC5

**Issue description:**
The physics documentation refers to Node2D scale handlers. If found the image confusing as it is not clear if the red circles are referring to the scale handlers or the correct size handlers. However, I don't see them anymore in the latest Godot version. Maybe they are only shown in certain cases, but I found some issues referring to their removal.
https://github.com/godotengine/godot/issues/21873

If they are really gone, I can create a pull request. If they aren't gone, let's make the documentation a bit more specific.

**URL to the documentation page:**
https://docs.godotengine.org/en/latest/tutorials/physics/physics_introduction.html