### Godot version

v4.2.dev.custom_build [c3b0a92c3]

### System information

Debian Linux X11 Xfce

### Issue description

In the following scene tree it is not possible to write anything in `LineEditB`.
![image](https://github.com/godotengine/godot/assets/6299227/ce5f696a-d86a-402f-98f7-6a762f15543e)

I would expect, that it is possible to focus `LineEditB` with a mouse click and write into it.

Regression from #58334

### Steps to reproduce

1. Load and run MRP
2. Mouse Click into the left LineEditB
3. Type Keyboard => No letters appear in the LineEditB

Variant:

1. Load and run MRP
2. Mouse Click into the right LineEditA
3. Mouse Click into the left LineEditB
4. Type Keyboard => Letters appear in LineEditA instead of LineEditB


### Minimal reproduction project

[BugKeyInputRouting.zip](https://github.com/godotengine/godot/files/11994804/BugKeyInputRouting.zip)

ERR_FAIL_COND(!is_inside_tree());
	for (int i = 0; i < gui.sub_windows.size(); i++) {
		ERR_FAIL_COND(gui.sub_windows[i].window == p_window);
	}
	if (gui.sub_windows.size() == 0) {
		subwindow_canvas = RS::get_singleton()->canvas_create();
		RS::get_singleton()->viewport_attach_canvas(viewport, subwindow_canvas);
		RS::get_singleton()->viewport_set_canvas_stacking(viewport, subwindow_canvas, SUBWINDOW_CANVAS_LAYER, 0);
	}
	SubWindow sw;
	sw.canvas_item = RS::get_singleton()->canvas_item_create();
	RS::get_singleton()->canvas_item_set_parent(sw.canvas_item, subwindow_canvas);
	sw.window = p_window;
	gui.sub_windows.push_back(sw);
	if (gui.subwindow_drag == SUB_WINDOW_DRAG_DISABLED) {
		if (p_window->get_flag(Window::FLAG_NO_FOCUS)) {
			_sub_window_update_order();
		} else {
			_sub_window_grab_focus(p_window);
		}
	} else {
		int index = _sub_window_find(gui.currently_dragged_subwindow);
		sw = gui.sub_windows[index];
		gui.sub_windows.remove_at(index);
		gui.sub_windows.push_back(sw);
		_sub_window_update_order();
	}
	RenderingServer::get_singleton()->viewport_set_parent_viewport(p_window->viewport, viewport);
}
void Viewport::_sub_window_update(Window *p_window) {