### 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
bool found = false;
	if (p_expression == nullptr) {
		return false;
	}
	static int recursion_depth = 0;
	RecursionCheck recursion(&recursion_depth);
	if (unlikely(recursion.check())) {
		ERR_FAIL_V_MSG(false, "Reached recursion limit while trying to guess type.");
	}
	if (p_expression->is_constant) {
		
		r_type = _type_from_variant(p_expression->reduced_value);
		switch (p_expression->get_datatype().kind) {
			case GDScriptParser::DataType::ENUM:
			case GDScriptParser::DataType::CLASS:
				r_type.type = p_expression->get_datatype();
				break;
			default:
				break;
		}
		found = true;
	} else {
		switch (p_expression->type) {
			case GDScriptParser::Node::LITERAL: {
				const GDScriptParser::LiteralNode *literal = static_cast<const GDScriptParser::LiteralNode *>(p_expression);
				r_type = _type_from_variant(literal->value);
				found = true;
			} break;
			case GDScriptParser::Node::SELF: {
				if (p_context.current_class) {