### 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
GDScriptParser::DataType type;
	String enumeration;
	Variant value;
	const GDScriptParser::ExpressionNode *assigned_expression = nullptr;
};
static int _get_property_location(StringName p_class, StringName p_property) {
	if (!ClassDB::has_property(p_class, p_property)) {
		return ScriptLanguage::LOCATION_OTHER;
	}
	int depth = 0;
	StringName class_test = p_class;
	while (class_test && !ClassDB::has_property(class_test, p_property, true)) {
		class_test = ClassDB::get_parent_class(class_test);
		depth++;
	}
	return depth | ScriptLanguage::LOCATION_PARENT_MASK;
}
static int _get_constant_location(StringName p_class, StringName p_constant) {
	if (!ClassDB::has_integer_constant(p_class, p_constant)) {
		return ScriptLanguage::LOCATION_OTHER;
	}
	int depth = 0;
	StringName class_test = p_class;
	while (class_test && !ClassDB::has_integer_constant(class_test, p_constant, true)) {
		class_test = ClassDB::get_parent_class(class_test);
		depth++;
	}
	return depth | ScriptLanguage::LOCATION_PARENT_MASK;
}
static int _get_signal_location(StringName p_class, StringName p_signal) {