### 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
} else {
							spec_constants |= SceneShaderGLES3::ADDITIVE_SPOT;
						}
						if (scene_state.positional_shadow_quality >= RS::SHADOW_QUALITY_SOFT_HIGH) {
							spec_constants |= SceneShaderGLES3::SHADOW_MODE_PCF_13;
						} else if (scene_state.positional_shadow_quality >= RS::SHADOW_QUALITY_SOFT_LOW) {
							spec_constants |= SceneShaderGLES3::SHADOW_MODE_PCF_5;
						}
					} else {
						
						uint32_t shadow_id = MAX_DIRECTIONAL_LIGHTS - 1 - (pass - int32_t(inst->light_passes.size()));
						if (pass == 0 && inst->lightmap_instance.is_valid() && scene_state.directional_lights[shadow_id].bake_mode == RenderingServer::LIGHT_BAKE_STATIC) {
							
							spec_constants &= ~SceneShaderGLES3::USE_ADDITIVE_LIGHTING;
						}
						if (scene_state.directional_shadows[shadow_id].shadow_split_offsets[0] == scene_state.directional_shadows[shadow_id].shadow_split_offsets[1]) {
							
						} else if (scene_state.directional_shadows[shadow_id].shadow_split_offsets[1] == scene_state.directional_shadows[shadow_id].shadow_split_offsets[2]) {
							spec_constants |= SceneShaderGLES3::LIGHT_USE_PSSM2;
						} else {
							spec_constants |= SceneShaderGLES3::LIGHT_USE_PSSM4;
						}
						if (scene_state.directional_shadows[shadow_id].blend_splits) {
							spec_constants |= SceneShaderGLES3::LIGHT_USE_PSSM_BLEND;
						}
						if (scene_state.directional_shadow_quality >= RS::SHADOW_QUALITY_SOFT_HIGH) {
							spec_constants |= SceneShaderGLES3::SHADOW_MODE_PCF_13;
						} else if (scene_state.directional_shadow_quality >= RS::SHADOW_QUALITY_SOFT_LOW) {
							spec_constants |= SceneShaderGLES3::SHADOW_MODE_PCF_5;
						}