### Godot version

4.0.beta16

### System information

Windows 10 Pro x64, GLES3, RTX 3080 Ti (528.02)

### Issue description

In Compatibility/GLES3 back-end, shaders which use a uniform to get the normal roughness buffer cannot compile. For example, the shader:
```glsl
shader_type spatial;

uniform sampler2D normal_roughness_texture : hint_normal_roughness_texture;

void fragment() {
    vec4 sample = texture(normal_roughness_texture, UV);
}
```
results in an error in the output:
```
  drivers/gles3/shader_gles3.cpp:242 - SceneShaderGLES3: Fragment shader compilation failed:
  0(890) : error C1503: undefined variable "normal_roughness_buffer"
  
  drivers/gles3/shader_gles3.cpp:342 - Method/function failed.
```

If I switch over to the Mobile or Forward+ backends, there is no shader compilation error.

### Steps to reproduce

Open the attached reproduction in the 4.0.beta16 editor.

When the scene is opened, the error is produced automatically:
1. Open `scene.tscn`
2. Open Output to review error

When the scene is saved with any changes made to the shader, the same error is also produced:
1. Open `scene.tscn`
2. Open `example.gdshader` in the shader editor.
3. Make a compile-able change to the shader.
4. Save the scene
5. Open Output to review the error

### Minimal reproduction project

[NormalRoughnessTexture_GLES3_Error.zip](https://github.com/godotengine/godot/files/10534253/NormalRoughnessTexture_GLES3_Error.zip)

if (uniform.repeat != REPEAT_DEFAULT) {
									if (uniform.repeat == new_repeat) {
										_set_error(vformat(RTR("Duplicated repeat mode: '%s'."), get_texture_repeat_name(new_repeat)));
									} else {
										_set_error(vformat(RTR("Redefinition of repeat mode: '%s'. The repeat mode has already been set to '%s'."), get_texture_repeat_name(new_repeat), get_texture_repeat_name(uniform.repeat)));
									}
									return ERR_PARSE_ERROR;
								} else {
									uniform.repeat = new_repeat;
									current_uniform_repeat = new_repeat;
								}
							}
							tk = _get_token();
						} while (tk.type == TK_COMMA);
					}
					if (uniform_scope == ShaderNode::Uniform::SCOPE_INSTANCE) {
						if (custom_instance_index >= 0) {
							uniform.instance_index = custom_instance_index;
						} else {
							uniform.instance_index = instance_index++;
							if (instance_index > MAX_INSTANCE_UNIFORM_INDICES) {
								_set_error(vformat(RTR("Too many '%s' uniforms in shader, maximum supported is %d."), "instance", MAX_INSTANCE_UNIFORM_INDICES));
								return ERR_PARSE_ERROR;
							}
						}
					}
					
					if (tk.type == TK_OP_ASSIGN) {
						if (uniform.array_size > 0) {
							_set_error(RTR("Setting default values to uniform arrays is not supported."));