### 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)

DataType data_type;
				if (tk.type == TK_IDENTIFIER) {
					bool is_const;
					_find_identifier(p_block, false, p_function_info, tk.text, &data_type, nullptr, &is_const);
					if (is_const) {
						if (data_type == TYPE_INT) {
							correct_constant_expression = true;
						}
					}
				}
				if (!correct_constant_expression) {
					_set_error(RTR("Expected an integer constant."));
					return ERR_PARSE_ERROR;
				}
				VariableNode *vn = alloc_node<VariableNode>();
				vn->name = tk.text;
				n = vn;
			} else {
				ConstantNode::Value v;
				if (tk.type == TK_UINT_CONSTANT) {
					v.uint = (uint32_t)tk.constant;
				} else {
					v.sint = (int)tk.constant * sign;
				}
				ConstantNode *cn = alloc_node<ConstantNode>();
				cn->values.push_back(v);
				cn->datatype = (tk.type == TK_UINT_CONSTANT ? TYPE_UINT : TYPE_INT);
				n = cn;
			}
			tk = _get_token();