### Godot version

4.1

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description


https://github.com/godotengine/godot/assets/2223172/3c8ee782-9d5f-42e3-a70f-d2aa59a233dd

We correctly clamp the size to 16x16 everywhere except here (probably).

### Steps to reproduce

1. Add a class with custom icon, e.g.
```GDScript
@icon("res://icon.svg")
extends Node
class_name Icon
```
2. Add it to scene
3. Open Script Editor and drag the node to script editor

### Minimal reproduction project

N/A
return selected;
}
void SceneTreeEditor::set_marked(const HashSet<Node *> &p_marked, bool p_selectable, bool p_children_selectable) {
	if (tree_dirty) {
		_update_tree();
	}
	marked = p_marked;
	marked_selectable = p_selectable;
	marked_children_selectable = p_children_selectable;
	_update_tree();
}
void SceneTreeEditor::set_marked(Node *p_marked, bool p_selectable, bool p_children_selectable) {
	HashSet<Node *> s;
	if (p_marked) {
		s.insert(p_marked);
	}
	set_marked(s, p_selectable, p_children_selectable);
}
void SceneTreeEditor::set_filter(const String &p_filter) {