### Godot version

4.0.0-beta-10

### System information

Windows 11

### Issue description

It appears that ImmediateMesh is always recalculating its own normals regardless of what is set.



### Steps to reproduce

1. Create MeshInstance3D node
2. Add [Tool] script and set mesh to ImmediateMesh
3. Use the following code in Process

```        
       if (Mesh is null)
            Mesh = new ImmediateMesh();

        if (Mesh is ImmediateMesh mesh)
        {
            mesh.ClearSurfaces();
            mesh.SurfaceBegin(Mesh.PrimitiveType.Triangles);

            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(-10, 10, -10f));
            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(10, 10, 10));
            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(-10, 10, 10));

            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(-10, 10, -10f));
            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(10, 10, -10));
            mesh.SurfaceSetNormal(new Vector3(0, 1, 0));
            mesh.SurfaceAddVertex(new Vector3(10, 10, 10));

            mesh.SurfaceEnd();
        }
```

You can either set the rendering for the scene to normals or you can get the array data and notice that the normals don't match what was set.

### Minimal reproduction project

.
RS::get_singleton()->mesh_clear(mesh);
	surfaces.clear();
	surface_active = false;
	colors.clear();
	normals.clear();
	tangents.clear();
	uvs.clear();
	uv2s.clear();
	vertices.clear();
	uses_colors = false;
	uses_normals = false;
	uses_tangents = false;
	uses_uvs = false;
	uses_uv2s = false;
}
int ImmediateMesh::get_surface_count() const {
	return surfaces.size();
}
int ImmediateMesh::surface_get_array_len(int p_idx) const {
	ERR_FAIL_INDEX_V(p_idx, int(surfaces.size()), -1);
	return surfaces[p_idx].array_len;
}
int ImmediateMesh::surface_get_array_index_len(int p_idx) const {