### 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
filter = p_filter;
	_update_filter(nullptr, true);
}
String SceneTreeEditor::get_filter() const {
	return filter;
}
String SceneTreeEditor::get_filter_term_warning() {
	return filter_term_warning;
}
void SceneTreeEditor::set_as_scene_tree_dock() {
	is_scene_tree_dock = true;
}
void SceneTreeEditor::set_display_foreign_nodes(bool p_display) {
	display_foreign = p_display;
	_update_tree();
}
void SceneTreeEditor::set_valid_types(const Vector<StringName> &p_valid) {
	valid_types = p_valid;
}
void SceneTreeEditor::set_editor_selection(EditorSelection *p_selection) {
	editor_selection = p_selection;
	tree->set_select_mode(Tree::SELECT_MULTI);
	tree->set_cursor_can_exit_tree(false);
	editor_selection->connect("selection_changed", callable_mp(this, &SceneTreeEditor::_selection_changed));
}
void SceneTreeEditor::_update_selection(TreeItem *item) {