### Godot version

4.0 rc1

### System information

Windows 11, GTX 1080Ti, Vulkan

### Issue description

Automplete can't find any variables and methods on custom classes when the nodes are loaded with `@onready`:

simple_rotate.gd:
```gdscript
extends Node2D
class_name SimpleRotate

@export var shouldRotate : bool = true
```

machine.gd:
```gdscript
@onready var wheel1 : SimpleRotate = $Wheel

func start_motor():
	wheel1.sho... # Doesn't autocomplete, it can't find shouldRotate 
```

If I add another cast like below, autocomplete does work:
machine.gd:
```gdscript
@onready var wheel1 : SimpleRotate = $Wheel as SimpleRotate

func start_motor():
	wheel1.shouldRotate = true # Autocomplete works
```

To make things even weirder, it does work if I make Wheel into a unique name and access it using %:
machine.gd:
```gdscript
@onready var wheel1 : SimpleRotate = $"%Wheel"

func start_motor():
	wheel1.shouldRotate = true # Autocomplete works
```


### Steps to reproduce

- Create a script with a class_name
- Add that script to a node
- Create another script referencing the node with the type of the script
- Try to let automcomplete find any methods or variables on the script with the class_name
- Notice that it fails

### Minimal reproduction project

N/A
return OK;
					}
				} else {
					List<StringName> utility_functions;
					Variant::get_utility_function_list(&utility_functions);
					if (utility_functions.find(p_symbol) != nullptr) {
						r_result.type = ScriptLanguage::LOOKUP_RESULT_CLASS_TBD_GLOBALSCOPE;
						r_result.class_name = "@GlobalScope";
						r_result.class_member = p_symbol;
						return OK;
					}
				}
			}
		} break;
		case GDScriptParser::COMPLETION_ATTRIBUTE_METHOD: {
			is_function = true;
			[[fallthrough]];
		}
		case GDScriptParser::COMPLETION_ATTRIBUTE: {
			if (context.node->type != GDScriptParser::Node::SUBSCRIPT) {
				break;
			}
			const GDScriptParser::SubscriptNode *subscript = static_cast<const GDScriptParser::SubscriptNode *>(context.node);
			if (!subscript->is_attribute) {
				break;
			}
			GDScriptCompletionIdentifier base;
			bool found_type = _get_subscript_type(context, subscript, base.type);
			if (!found_type && !_guess_expression_type(context, subscript->base, base)) {
				break;