### 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)

StructNode *pstruct = nullptr;
			bool struct_init = false;
			_get_completable_identifier(p_block, COMPLETION_IDENTIFIER, identifier);
			if (shader->structs.has(identifier)) {
				pstruct = shader->structs[identifier].shader_struct;
				struct_init = true;
			}
			tk = _get_token();
			if (tk.type == TK_PARENTHESIS_OPEN) {
				if (struct_init) { 
					const StringName &name = identifier;
					OperatorNode *func = alloc_node<OperatorNode>();
					func->op = OP_STRUCT;
					func->struct_name = name;
					func->return_cache = TYPE_STRUCT;
					VariableNode *funcname = alloc_node<VariableNode>();
					funcname->name = name;
					func->arguments.push_back(funcname);
					for (int i = 0; i < pstruct->members.size(); i++) {
						Node *nexpr;
						if (pstruct->members[i]->array_size != 0) {
							nexpr = _parse_array_constructor(p_block, p_function_info, pstruct->members[i]->get_datatype(), pstruct->members[i]->struct_name, pstruct->members[i]->array_size);
							if (!nexpr) {
								return nullptr;
							}
						} else {
							nexpr = _parse_and_reduce_expression(p_block, p_function_info);
							if (!nexpr) {
								return nullptr;
							}