### 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
} break;
				default:
					
					break;
			}
		}
		if (suite->parent_if && suite->parent_if->condition && suite->parent_if->condition->type == GDScriptParser::Node::TYPE_TEST) {
			
			
			
			
			const GDScriptParser::TypeTestNode *type_test = static_cast<const GDScriptParser::TypeTestNode *>(suite->parent_if->condition);
			if (type_test->operand && type_test->test_type && type_test->operand->type == GDScriptParser::Node::IDENTIFIER && static_cast<const GDScriptParser::IdentifierNode *>(type_test->operand)->name == p_identifier->name && static_cast<const GDScriptParser::IdentifierNode *>(type_test->operand)->source == p_identifier->source) {
				
				GDScriptParser::CompletionContext c = p_context;
				c.current_line = type_test->operand->start_line;
				c.current_suite = suite;
				if (type_test->test_datatype.is_hard_type()) {
					id_type = type_test->test_datatype;
					if (last_assign_line < c.current_line) {
						
						last_assign_line = c.current_line;
						last_assigned_expression = nullptr;
					}
				}
			}
		}
		suite = suite->parent_block;
	}
	if (last_assigned_expression && last_assign_line < p_context.current_line) {