### 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 (!p_context.current_suite) {
		return;
	}
	for (int i = 0; i < p_context.current_suite->statements.size(); i++) {
		if (p_context.current_suite->statements[i]->start_line < r_last_return_line) {
			break;
		}
		GDScriptParser::CompletionContext c = p_context;
		switch (p_context.current_suite->statements[i]->type) {
			case GDScriptParser::Node::FOR:
				c.current_suite = static_cast<const GDScriptParser::ForNode *>(p_context.current_suite->statements[i])->loop;
				_find_last_return_in_block(c, r_last_return_line, r_last_returned_value);
				break;
			case GDScriptParser::Node::WHILE:
				c.current_suite = static_cast<const GDScriptParser::WhileNode *>(p_context.current_suite->statements[i])->loop;
				_find_last_return_in_block(c, r_last_return_line, r_last_returned_value);
				break;
			case GDScriptParser::Node::IF: {