### 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
}
			_update_visibility_color(p_node, item);
		} else if (p_node->is_class("CanvasLayer") || p_node->is_class("Window")) {
			bool v = p_node->call("is_visible");
			if (v) {
				item->add_button(0, get_theme_icon(SNAME("GuiVisibilityVisible"), SNAME("EditorIcons")), BUTTON_VISIBILITY, false, TTR("Toggle Visibility"));
			} else {
				item->add_button(0, get_theme_icon(SNAME("GuiVisibilityHidden"), SNAME("EditorIcons")), BUTTON_VISIBILITY, false, TTR("Toggle Visibility"));
			}
			if (!p_node->is_connected("visibility_changed", callable_mp(this, &SceneTreeEditor::_node_visibility_changed))) {
				p_node->connect("visibility_changed", callable_mp(this, &SceneTreeEditor::_node_visibility_changed).bind(p_node));
			}
		} else if (p_node->is_class("Node3D")) {
			if (p_node->has_meta("_edit_lock_")) {
				item->add_button(0, get_theme_icon(SNAME("Lock"), SNAME("EditorIcons")), BUTTON_LOCK, false, TTR("Node is locked.\nClick to unlock it."));
			}
			if (p_node->has_meta("_edit_group_")) {
				item->add_button(0, get_theme_icon(SNAME("Group"), SNAME("EditorIcons")), BUTTON_GROUP, false, TTR("Children are not selectable.\nClick to make them selectable."));
			}
			bool v = p_node->call("is_visible");
			if (v) {
				item->add_button(0, get_theme_icon(SNAME("GuiVisibilityVisible"), SNAME("EditorIcons")), BUTTON_VISIBILITY, false, TTR("Toggle Visibility"));
			} else {
				item->add_button(0, get_theme_icon(SNAME("GuiVisibilityHidden"), SNAME("EditorIcons")), BUTTON_VISIBILITY, false, TTR("Toggle Visibility"));
			}
			if (!p_node->is_connected("visibility_changed", callable_mp(this, &SceneTreeEditor::_node_visibility_changed))) {
				p_node->connect("visibility_changed", callable_mp(this, &SceneTreeEditor::_node_visibility_changed).bind(p_node));
			}
			_update_visibility_color(p_node, item);
		} else if (p_node->is_class("AnimationPlayer")) {