Vehiclebody3D sliding down slope when parked

### Tested versions

- Tested in 4.2.1 stable

### System information

Windows 10 - Godot 4.2.1 stable - compatibility

### Issue description

A Vehiclebody3D parked sideways on a slope will slide down. Depending on gravity, friction, roll influence and spring settings it will slide more or less but it will never stand still unless the gravity is 0.
It's even possible with the right combination of settings to make the vehicle slide up the slope. This is without any engine force or steering applied!


### Steps to reproduce

Run the demo project

### Minimal reproduction project (MRP)

[VehicleBody Slope.zip](https://github.com/godotengine/godot/files/14443066/VehicleBody.Slope.zip)

Start by running the linked VehicleBody Slope.zip minimal reproduction project and inspect the sideways parked VehicleBody3D on a slope under the reported Godot 4.2.1 compatibility setup. Compare behavior across the gravity, friction, roll influence, and spring settings shown in the report; done means the vehicle remains parked without engine force or steering when the reproduction conditions are met.

Written by the indexing model from the issue text.