### 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
AnimationPlayer *player = AnimationPlayerEditor::get_singleton()->get_player();
	if (player->has_animation(SceneStringNames::get_singleton()->RESET)) {
		return player->get_animation(SceneStringNames::get_singleton()->RESET);
	} else {
		Ref<AnimationLibrary> al;
		if (!player->has_animation_library("")) {
			al.instantiate();
			player->add_animation_library("", al);
		} else {
			al = player->get_animation_library("");
		}
		Ref<Animation> reset_anim;
		reset_anim.instantiate();
		reset_anim->set_length(ANIM_MIN_LENGTH);
		EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
		undo_redo->add_do_method(al.ptr(), "add_animation", SceneStringNames::get_singleton()->RESET, reset_anim);
		undo_redo->add_do_method(AnimationPlayerEditor::get_singleton(), "_animation_player_changed", player);
		undo_redo->add_undo_method(al.ptr(), "remove_animation", SceneStringNames::get_singleton()->RESET);
		undo_redo->add_undo_method(AnimationPlayerEditor::get_singleton(), "_animation_player_changed", player);
		return reset_anim;
	}
}
void AnimationTrackEditor::_confirm_insert_list() {