### 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
}
		case GDScriptParser::COMPLETION_ASSIGN:
		case GDScriptParser::COMPLETION_CALL_ARGUMENTS:
		case GDScriptParser::COMPLETION_IDENTIFIER:
		case GDScriptParser::COMPLETION_PROPERTY_METHOD: {
			GDScriptParser::DataType base_type;
			if (context.current_class) {
				if (context.type != GDScriptParser::COMPLETION_SUPER_METHOD) {
					base_type = context.current_class->get_datatype();
				} else {
					base_type = context.current_class->base_type;
				}
			} else {
				break;
			}
			if (!is_function && context.current_suite) {
				
				const GDScriptParser::SuiteNode *suite = context.current_suite;
				while (suite) {
					if (suite->has_local(p_symbol)) {
						r_result.type = ScriptLanguage::LOOKUP_RESULT_SCRIPT_LOCATION;
						r_result.location = suite->get_local(p_symbol).start_line;
						return OK;
					}
					suite = suite->parent_block;
				}
			}
			if (_lookup_symbol_from_base(base_type, p_symbol, is_function, r_result) == OK) {
				return OK;
			}