### Godot version

4.0 Stable

### System information

Ubuntu 22.04

### Issue description

Setting fog_affect_sky = 1 do not have the desired effect when using a Color sky mode. It works properly if we use a procedural sky or the forward+ renderer.

![Screenshot from 2023-03-03 16-50-53](https://user-images.githubusercontent.com/8985409/222870514-0195c4cb-bbca-4e9b-bb6a-6e2a568d2f7b.png)


### Steps to reproduce

Add a sky with a plain color mode like the Clear Color default option. Enable fog and set fog_affect_sky value to 1. Sky is still not affected by fog. 

### Minimal reproduction project
[mobile_fog_sky_bug.zip](https://github.com/godotengine/godot/files/10887265/mobile_fog_sky_bug.zip)


textures.push_back(vrs_texture); 
	}
	if (use_msaa) {
		color_buffer_id = textures.size();
		textures.push_back(render_buffers->get_internal_texture()); 
		
	}
	
	Vector<RD::FramebufferPass> passes;
	
	RD::FramebufferPass pass;
	pass.color_attachments.push_back(0);
	pass.depth_attachment = 1;
	if (vrs_texture.is_valid()) {
		pass.vrs_attachment = 2;
	}
	switch (p_config_type) {
		case FB_CONFIG_ONE_PASS: {
			
			if (use_msaa) {
				
				pass.resolve_attachments.push_back(color_buffer_id);
			}
			passes.push_back(pass);
			return FramebufferCacheRD::get_singleton()->get_cache_multipass(textures, passes, view_count);
		} break;
		case FB_CONFIG_TWO_SUBPASSES: {
			
			passes.push_back(pass);