### 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
if (!editor_selection) {
		return;
	}
	TreeItem *root = tree->get_root();
	if (!root) {
		return;
	}
	_update_selection(root);
}
void SceneTreeEditor::_cell_collapsed(Object *p_obj) {
	if (updating_tree) {
		return;
	}
	if (!can_rename) {
		return;
	}
	TreeItem *ti = Object::cast_to<TreeItem>(p_obj);
	if (!ti) {
		return;
	}
	bool collapsed = ti->is_collapsed();
	NodePath np = ti->get_metadata(0);
	Node *n = get_node(np);
	ERR_FAIL_COND(!n);
	n->set_display_folded(collapsed);
}
Variant SceneTreeEditor::get_drag_data_fw(const Point2 &p_point, Control *p_from) {