GPUParticlesCollisionHeightField3D not working in mobile renderer

### Tested versions

Godot v4.5.1.stable

### System information

macOS Sequoia (15.7.2) - Multi-window, 1 monitor - OpenGL 3 (Compatibility) - Apple M4 Pro - Apple M4 Pro (14 threads) - 48.00 GiB memory

### Issue description

Particles are not colliding with the heigh field

The collision works the `Forward+` and `Compatibility` renderer, but not with `Mobile`

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### Steps to reproduce

I have a very simple scene:

* GPU Particles
* CSG Box
* Particle collision heigh field

### Minimal reproduction project (MRP)

[test.zip](https://github.com/user-attachments/files/23554650/test.zip)