### Godot version

3b086aa06

### System information

ArchLinux x11

### Issue description

```gdscript
extends Node

@export_group("My Properties")
@export var number = 3
@export var string = ""

@export_group("Prefixed Properties", "prefix_")
@export var prefix_number = 3
@export var prefix_string = ""

@export_group("", "")
@export var ungrouped_number = 3
```

![image](https://user-images.githubusercontent.com/70787919/214983963-528c415b-745b-47fc-9777-36ebe31a3060.png)


### Steps to reproduce

- create script
- @export_group
- go inspector

### Minimal reproduction project

‮
AnnotationNode *annotation = const_cast<AnnotationNode *>(p_annotation);
	annotation->export_info.name = annotation->resolved_arguments[0];
	switch (t_usage) {
		case PROPERTY_USAGE_CATEGORY: {
			annotation->export_info.usage = t_usage;
		} break;
		case PROPERTY_USAGE_GROUP: {
			annotation->export_info.usage = t_usage;
			if (annotation->resolved_arguments.size() == 2) {
				annotation->export_info.hint_string = annotation->resolved_arguments[1];
			}
		} break;
		case PROPERTY_USAGE_SUBGROUP: {
			annotation->export_info.usage = t_usage;
			if (annotation->resolved_arguments.size() == 2) {
				annotation->export_info.hint_string = annotation->resolved_arguments[1];
			}
		} break;
	}
	current_class->add_member_group(annotation);
	return true;
}
bool GDScriptParser::warning_annotations(const AnnotationNode *p_annotation, Node *p_node) {