### 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 (p_node->type == Node::TYPE_OPERATOR) {
		OperatorNode *op = static_cast<OperatorNode *>(p_node);
		if (op->op == OP_INDEX) {
			return _validate_assign(op->arguments[0], p_function_info, r_message);
		} else if (_is_operator_assign(op->op)) {
			
			return _validate_assign(op->arguments[1], p_function_info, r_message);
		} else if (op->op == OP_CALL) {
			if (r_message) {
				*r_message = RTR("Assignment to function.");
			}
			return false;
		}
	} else if (p_node->type == Node::TYPE_MEMBER) {
		MemberNode *member = static_cast<MemberNode *>(p_node);
		if (member->has_swizzling_duplicates) {
			if (r_message) {
				*r_message = RTR("Swizzling assignment contains duplicates.");
			}
			return false;
		}
		return _validate_assign(member->owner, p_function_info, r_message);
	} else if (p_node->type == Node::TYPE_VARIABLE) {
		VariableNode *var = static_cast<VariableNode *>(p_node);
		if (shader->uniforms.has(var->name)) {