### Godot version

4.2.dev 5ee983188de97ae027f9b9c1443438063f708a7e

### System information

Windows 10 - Compatibility renderer 

### Issue description

When running a VR project sky contribution is not working in the compatibility renderer:

![image](https://github.com/godotengine/godot/assets/1945449/7aa19569-95c8-41a2-913b-37b81f4728a7)

It is working fine in normal mode. Can be worked around by setting sky contribution to 0 and providing an ambient color.

### Steps to reproduce

Try any project with a proper sky setup in XR, just switch to compatibility renderer.

### Minimal reproduction project

I'll try and create an MVP soon that can be used without XR hardware, but for now this can be used:
https://github.com/BastiaanOlij/godot_openxr_demo
sky_globals.default_material = material_storage->material_allocate();
		material_storage->material_initialize(sky_globals.default_material);
		material_storage->material_set_shader(sky_globals.default_material, sky_globals.default_shader);
	}
	{
		sky_globals.fog_shader = material_storage->shader_allocate();
		material_storage->shader_initialize(sky_globals.fog_shader);
		material_storage->shader_set_code(sky_globals.fog_shader, R"(
// Default clear color sky shader.
shader_type sky;
uniform vec4 clear_color;
void sky() {
	COLOR = clear_color.rgb;
}
)");
		sky_globals.fog_material = material_storage->material_allocate();
		material_storage->material_initialize(sky_globals.fog_material);
		material_storage->material_set_shader(sky_globals.fog_material, sky_globals.fog_shader);
	}
	{
		glGenVertexArrays(1, &sky_globals.screen_triangle_array);
		glBindVertexArray(sky_globals.screen_triangle_array);
		glGenBuffers(1, &sky_globals.screen_triangle);
		glBindBuffer(GL_ARRAY_BUFFER, sky_globals.screen_triangle);
		const float qv[6] = {
			-1.0f,
			-1.0f,
			3.0f,
			-1.0f,
			-1.0f,