### 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 (!p_parent) {
		p_parent = tree->get_root();
		filter_term_warning.clear();
	}
	if (!p_parent) {
		// Tree is empty, nothing to do here.
		return false;
	}
	bool keep_for_children = false;
	for (TreeItem *child = p_parent->get_first_child(); child; child = child->get_next()) {
		// Always keep if at least one of the children are kept.
		keep_for_children = _update_filter(child, p_scroll_to_selected) || keep_for_children;
	}
	// Now find other reasons to keep this Node, too.
	PackedStringArray terms = filter.to_lower().split_spaces();
	bool keep = _item_matches_all_terms(p_parent, terms);
	p_parent->set_visible(keep_for_children || keep);
	if (keep && !valid_types.is_empty()) {
		keep = false;
		Node *n = get_node(p_parent->get_metadata(0));
		for (const StringName &E : valid_types) {
			if (n->is_class(E) ||
					EditorNode::get_singleton()->is_object_of_custom_type(n, E)) {
				keep = true;
				break;