### 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
r_type.type.kind = GDScriptParser::DataType::BUILTIN;
					r_type.type.builtin_type = GDScriptParser::get_builtin_type(call->function_name);
					found = true;
					break;
				} else if (GDScriptUtilityFunctions::function_exists(call->function_name)) {
					MethodInfo mi = GDScriptUtilityFunctions::get_function_info(call->function_name);
					r_type = _type_from_property(mi.return_val);
					found = true;
					break;
				} else {
					GDScriptParser::CompletionContext c = p_context;
					c.current_line = call->start_line;
					GDScriptParser::Node::Type callee_type = call->get_callee_type();
					GDScriptCompletionIdentifier base;
					if (callee_type == GDScriptParser::Node::IDENTIFIER || call->is_super) {
						
						if (p_context.current_class) {
							if (call->is_super) {
								base.type = p_context.current_class->base_type;
								base.value = p_context.base;
							} else {
								base.type.kind = GDScriptParser::DataType::CLASS;
								base.type.type_source = GDScriptParser::DataType::INFERRED;
								base.type.is_constant = true;
								base.type.class_type = p_context.current_class;
								base.value = p_context.base;
							}
						} else {
							break;
						}