### Godot version

4.1.3

### System information

Linux

### Issue description

I'm trying to make an editor plugin on Rust:

```rust
#[derive(GodotClass)]
#[class(tool, editor_plugin, init, base=EditorPlugin)]
pub struct MyEditorPluginBase {}
```

But due to some limitations, I still have to use GDScript for some specific things.

So I tried to make a subclass of this Rust class:

```gdscript
@tool
class_name MyEditorPlugin
extends MyEditorPluginBase
```

This would work if `MyEditorPluginBase` was a GDScript class, but since it's a GDExtension class in my case, it doesn't work:

> Unable to load addon script from path: 'res://addons/my_addon/my_editor_plugin.gd' Base type is not EditorPlugin.

But it obviously **IS** EditorPlugin!

![godot-editorplugin-docs](https://github.com/godotengine/godot/assets/3236464/4665deeb-30f0-45cd-bfff-56101b9d4875)

![godot-editorplugin](https://github.com/godotengine/godot/assets/3236464/b1b6ecb4-de22-4abd-91a3-e180691f67ee)

If I understand correctly, this behavior is caused by this function, which checks some mysterious "instance base type" instead of real inheritance:

https://github.com/godotengine/godot/blob/fa4a65387ea41506ecc519fc61a06da110dce51c/editor/editor_node.cpp#L3456-L3458

https://github.com/godotengine/godot/blob/fa4a65387ea41506ecc519fc61a06da110dce51c/modules/gdscript/gdscript.cpp#L260-L263

Since the [documentation](https://docs.godotengine.org/en/stable/tutorials/plugins/editor/making_plugins.html#the-script-file) doesn't say that the script must be a **direct** subclass of EditorPlugin (and an indirect subclass works fine in GDScript), I interpret this behavior as a Godot bug.

### Steps to reproduce

See above

### Minimal reproduction project

[gdext_editor_plugin_test.zip](https://github.com/godotengine/godot/files/13451014/gdext_editor_plugin_test.zip)
}
		String found_base_class;
		StringName base_class = script->get_instance_base_type();
		Ref<Script> inherited_script = script->get_base_script();
		while (!inherited_script.is_null()) {
			if (inherited_script->has_method(name)) {
				found_base_class = "script:" + inherited_script->get_path();
				break;
			}
			base_class = inherited_script->get_instance_base_type();
			inherited_script = inherited_script->get_base_script();
		}
		if (found_base_class.is_empty()) {
			while (base_class) {
				List<MethodInfo> methods;
				ClassDB::get_method_list(base_class, &methods, true);
				for (int j = 0; j < methods.size(); j++) {
					if (methods[j].name == name) {
						found_base_class = "builtin:" + base_class;
						break;
					}
				}
				ClassDB::ClassInfo *base_class_ptr = ClassDB::classes.getptr(base_class)->inherits_ptr;
				if (base_class_ptr == nullptr) {
					break;
				}
				base_class = base_class_ptr->name;
			}
		}
		if (!found_base_class.is_empty()) {