### 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
List<MethodInfo> constructors;
		Variant::get_constructor_list(GDScriptParser::get_builtin_type(call->function_name), &constructors);
		int i = 0;
		for (const MethodInfo &E : constructors) {
			if (p_argidx >= E.arguments.size()) {
				continue;
			}
			if (i > 0) {
				r_arghint += "\n";
			}
			r_arghint += _make_arguments_hint(E, p_argidx);
			i++;
		}
		return;
	} else if (call->is_super || callee_type == GDScriptParser::Node::IDENTIFIER) {
		base = p_context.base;
		if (p_context.current_class) {
			base_type = p_context.current_class->get_datatype();
			_static = !p_context.current_function || p_context.current_function->is_static;
		}
	} else {
		return;
	}
	GDScriptCompletionIdentifier ci;
	ci.type = base_type;
	ci.value = base;
	_find_call_arguments(p_context, ci, call->function_name, p_argidx, _static, r_result, r_arghint);
	r_forced = r_result.size() > 0;
}
::Error GDScriptLanguage::complete_code(const String &p_code, const String &p_path, Object *p_owner, List<ScriptLanguage::CodeCompletionOption> *r_options, bool &r_forced, String &r_call_hint) {