### 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
Vector3(0, +1, 0),
			Vector3(0, -1, 0),
			Vector3(0, 0, +1),
			Vector3(0, 0, -1)
		};
		static const Vector3 view_up[6] = {
			Vector3(0, -1, 0),
			Vector3(0, -1, 0),
			Vector3(0, 0, +1),
			Vector3(0, 0, -1),
			Vector3(0, -1, 0),
			Vector3(0, -1, 0)
		};
		Projection cm;
		cm.set_perspective(90, 1, 0.01, 10.0);
		Projection correction;
		correction.columns[1][1] = -1.0;
		cm = correction * cm;
		bool success = material_storage->shaders.sky_shader.version_bind_shader(shader_data->version, SkyShaderGLES3::MODE_CUBEMAP);
		if (!success) {
			return;
		}
		material_storage->shaders.sky_shader.version_set_uniform(SkyShaderGLES3::POSITION, p_transform.origin, shader_data->version, SkyShaderGLES3::MODE_CUBEMAP);
		material_storage->shaders.sky_shader.version_set_uniform(SkyShaderGLES3::TIME, time, shader_data->version, SkyShaderGLES3::MODE_CUBEMAP);
		material_storage->shaders.sky_shader.version_set_uniform(SkyShaderGLES3::PROJECTION, cm.columns[2][0], cm.columns[0][0], cm.columns[2][1], cm.columns[1][1], shader_data->version, SkyShaderGLES3::MODE_CUBEMAP);
		material_storage->shaders.sky_shader.version_set_uniform(SkyShaderGLES3::LUMINANCE_MULTIPLIER, p_luminance_multiplier, shader_data->version, SkyShaderGLES3::MODE_CUBEMAP);
		glBindVertexArray(sky_globals.screen_triangle_array);
		glViewport(0, 0, sky->radiance_size, sky->radiance_size);
		glBindFramebuffer(GL_FRAMEBUFFER, sky->radiance_framebuffer);
		glDisable(GL_BLEND);