### Tested versions

- Reproducible in: v4.2.stable.arch_linux
- Not Reproducible in: v4.1.3.stable.official [f06b6836a]

### System information

Garuda Linux (2.6.19-2)

### Issue description

A minor issue where UI Icons are not rendering on the Group Editor window, attaching a screenshot for reference:
![Screenshot_604](https://github.com/godotengine/godot/assets/22623256/c366164a-3d9a-4dcf-97a0-199b5a5a7ecc)

The icons were expected for Buttons like Add, Remove, Filter, etc.

### Steps to reproduce

Select any Node and go to the `Node` panel, click `Manage Groups` and the window will open.

### Minimal reproduction project (MRP)

Minor issue, easily reproducible following the above steps.
groups->connect("item_edited", callable_mp(this, &GroupDialog::_group_renamed));
	HBoxContainer *chbc = memnew(HBoxContainer);
	vbc_left->add_child(chbc);
	chbc->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	add_group_text = memnew(LineEdit);
	chbc->add_child(add_group_text);
	add_group_text->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	add_group_text->connect("text_submitted", callable_mp(this, &GroupDialog::_add_group_pressed));
	add_group_text->connect("text_changed", callable_mp(this, &GroupDialog::_add_group_text_changed));
	add_group_button = memnew(Button);
	add_group_button->set_text(TTR("Add"));
	chbc->add_child(add_group_button);
	add_group_button->connect("pressed", callable_mp(this, &GroupDialog::_add_group_pressed).bind(String()));
	VBoxContainer *vbc_add = memnew(VBoxContainer);
	hbc->add_child(vbc_add);
	vbc_add->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	Label *out_of_group_title = memnew(Label);
	out_of_group_title->set_theme_type_variation("HeaderSmall");
	out_of_group_title->set_text(TTR("Nodes Not in Group"));
	vbc_add->add_child(out_of_group_title);
	nodes_to_add = memnew(Tree);
	vbc_add->add_child(nodes_to_add);
	nodes_to_add->set_hide_root(true);
	nodes_to_add->set_hide_folding(true);
	nodes_to_add->set_select_mode(Tree::SELECT_MULTI);
	nodes_to_add->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	nodes_to_add->add_theme_constant_override("draw_guides", 1);
	HBoxContainer *add_filter_hbc = memnew(HBoxContainer);
	add_filter_hbc->add_theme_constant_override("separate", 0);
	vbc_add->add_child(add_filter_hbc);