### 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
}
			if (!type.enumeration.is_empty()) {
				_find_enumeration_candidates(completion_context, type.enumeration, options);
				r_forced = options.size() > 0;
			} else {
				_find_identifiers(completion_context, false, options, 0);
				r_forced = true;
			}
		} break;
		case GDScriptParser::COMPLETION_METHOD:
			is_function = true;
			[[fallthrough]];
		case GDScriptParser::COMPLETION_IDENTIFIER: {
			_find_identifiers(completion_context, is_function, options, 0);
		} break;
		case GDScriptParser::COMPLETION_ATTRIBUTE_METHOD:
			is_function = true;
			[[fallthrough]];
		case GDScriptParser::COMPLETION_ATTRIBUTE: {
			r_forced = true;
			const GDScriptParser::SubscriptNode *attr = static_cast<const GDScriptParser::SubscriptNode *>(completion_context.node);
			if (attr->base) {
				GDScriptCompletionIdentifier base;
				bool found_type = _get_subscript_type(completion_context, attr, base.type);
				if (!found_type && !_guess_expression_type(completion_context, attr->base, base)) {
					break;
				}
				_find_identifiers_in_base(base, is_function, options, 0);
			}
		} break;