### 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_MAIN_THREAD_GUARD;
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			_update_viewport_path();
			if (get_parent()) {
				parent = get_parent()->get_viewport();
				RenderingServer::get_singleton()->viewport_set_parent_viewport(viewport, parent->get_viewport_rid());
			} else {
				parent = nullptr;
			}
			current_canvas = find_world_2d()->get_canvas();
			RenderingServer::get_singleton()->viewport_attach_canvas(viewport, current_canvas);
			RenderingServer::get_singleton()->viewport_set_canvas_transform(viewport, current_canvas, canvas_transform);
			RenderingServer::get_singleton()->viewport_set_canvas_cull_mask(viewport, canvas_cull_mask);
			_update_audio_listener_2d();
#ifndef _3D_DISABLED
			RenderingServer::get_singleton()->viewport_set_scenario(viewport, find_world_3d()->get_scenario());
			_update_audio_listener_3d();
#endif 
			add_to_group("_viewports");
			if (get_tree()->is_debugging_collisions_hint()) {
				PhysicsServer2D::get_singleton()->space_set_debug_contacts(find_world_2d()->get_space(), get_tree()->get_collision_debug_contact_count());
				contact_2d_debug = RenderingServer::get_singleton()->canvas_item_create();
				RenderingServer::get_singleton()->canvas_item_set_parent(contact_2d_debug, current_canvas);
#ifndef _3D_DISABLED
				PhysicsServer3D::get_singleton()->space_set_debug_contacts(find_world_3d()->get_space(), get_tree()->get_collision_debug_contact_count());