### Godot version

4.2 dev3

### 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

If you have a Method Track with multiple calls to the same method, they are joined together and makes things unreadable:
![image](https://github.com/godotengine/godot/assets/2223172/a2ab8446-28a1-440b-b0d5-5049f5d705b4)
The horizontal line shouldn't be used here. I think it might be a regression.

### Steps to reproduce

1. Add AnimationPlayer
2. Add a Method Track (with Add Track button)
3. Add some key to the track
4. Add another key with the same method

### Minimal reproduction project

N/A
bottom_hb->add_spacer();
	bezier_edit_icon = memnew(Button);
	bezier_edit_icon->set_flat(true);
	bezier_edit_icon->set_disabled(true);
	bezier_edit_icon->set_toggle_mode(true);
	bezier_edit_icon->connect("pressed", callable_mp(this, &AnimationTrackEditor::_toggle_bezier_edit));
	bezier_edit_icon->set_tooltip_text(TTR("Toggle between the bezier curve editor and track editor."));
	bottom_hb->add_child(bezier_edit_icon);
	selected_filter = memnew(Button);
	selected_filter->set_flat(true);
	selected_filter->connect("pressed", callable_mp(this, &AnimationTrackEditor::_view_group_toggle)); 
	selected_filter->set_toggle_mode(true);
	selected_filter->set_tooltip_text(TTR("Only show tracks from nodes selected in tree."));
	bottom_hb->add_child(selected_filter);
	view_group = memnew(Button);
	view_group->set_flat(true);
	view_group->connect("pressed", callable_mp(this, &AnimationTrackEditor::_view_group_toggle));
	view_group->set_toggle_mode(true);
	view_group->set_tooltip_text(TTR("Group tracks by node or display them as plain list."));
	bottom_hb->add_child(view_group);
	bottom_hb->add_child(memnew(VSeparator));
	snap = memnew(Button);
	snap->set_flat(true);
	snap->set_text(TTR("Snap:") + " ");
	bottom_hb->add_child(snap);
	snap->set_disabled(true);
	snap->set_toggle_mode(true);
	snap->set_pressed(true);
	step = memnew(EditorSpinSlider);
	step->set_min(0);