### 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
} else if (callee_type == GDScriptParser::Node::SUBSCRIPT && static_cast<const GDScriptParser::SubscriptNode *>(call->callee)->is_attribute) {
						if (!_guess_expression_type(c, static_cast<const GDScriptParser::SubscriptNode *>(call->callee)->base, base)) {
							found = false;
							break;
						}
					} else {
						break;
					}
					
					if (base.type.is_constant && base.value.get_type() == Variant::OBJECT) {
						GDScriptParser::DataType native_type = base.type;
						while (native_type.kind == GDScriptParser::DataType::CLASS) {
							native_type = native_type.class_type->base_type;
						}
						while (native_type.kind == GDScriptParser::DataType::SCRIPT) {
							if (native_type.script_type.is_valid()) {
								Ref<Script> parent = native_type.script_type->get_base_script();
								if (parent.is_valid()) {
									native_type.script_type = parent;
								} else {
									native_type.kind = GDScriptParser::DataType::NATIVE;
									native_type.builtin_type = Variant::OBJECT;
									native_type.native_type = native_type.script_type->get_instance_base_type();
									if (!ClassDB::class_exists(native_type.native_type)) {
										native_type.kind = GDScriptParser::DataType::UNRESOLVED;
									}
								}
							}
						}
						if (native_type.kind == GDScriptParser::DataType::NATIVE) {