### Godot version

4.1.1

### System information

windows 11

### Issue description

When registering a type with class_name and using that class name to declare a variable in code only, autocomplete works as expected anywhere in other nodes/scenes. However, if making a custom scene node that extends a script with the class_name, if that custom scene is instantiated in a different scene, even if the type is specified, it only shows the parent node's functions and not any of the extended functionality. I have made a basic project showing the issue

### Steps to reproduce

I have made a very simple project showing the issue. https://github.com/mmmmmmmmmmmmmmmmmmmdonuts/godot_4_autocomplete_issue essentially, the extended Node scene will only show the custom function when both the type is specified as well as the type afterwards following "as" 
e.g. `@onready var my_class_4: MyClass = $MyClass4 as MyClass`

### Minimal reproduction project

https://github.com/mmmmmmmmmmmmmmmmmmmdonuts/godot_4_autocomplete_issue
}
		}
		return false;
	} else {
		const GDScriptParser::ClassNode *cl = parser.get_tree();
		HashMap<int, String> funcs;
		get_function_names_recursively(cl, "", funcs);
		for (const KeyValue<int, String> &E : funcs) {
			r_functions->push_back(E.value + ":" + itos(E.key));
		}
	}
#ifdef DEBUG_ENABLED
	if (r_safe_lines) {
		const HashSet<int> &unsafe_lines = parser.get_unsafe_lines();
		for (int i = 1; i <= parser.get_last_line_number(); i++) {
			if (!unsafe_lines.has(i)) {
				r_safe_lines->insert(i);
			}
		}
	}
#endif
	return true;
}
bool GDScriptLanguage::supports_builtin_mode() const {
	return true;
}
bool GDScriptLanguage::supports_documentation() const {
	return true;
}
int GDScriptLanguage::find_function(const String &p_function, const String &p_code) const {