### 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)

for (int i = 0; i < get_child_count(); i++) {
				SubViewport *c = Object::cast_to<SubViewport>(get_child(i));
				if (!c) {
					continue;
				}
				if (stretch) {
					draw_texture_rect(c->get_texture(), Rect2(Vector2(), get_size()));
				} else {
					draw_texture_rect(c->get_texture(), Rect2(Vector2(), c->get_size()));
				}
			}
		} break;
		case NOTIFICATION_MOUSE_ENTER: {
			_notify_viewports(NOTIFICATION_VP_MOUSE_ENTER);
		} break;
		case NOTIFICATION_MOUSE_EXIT: {
			_notify_viewports(NOTIFICATION_VP_MOUSE_EXIT);
		} break;
	}
}
void SubViewportContainer::_notify_viewports(int p_notification) {
	for (int i = 0; i < get_child_count(); i++) {
		SubViewport *c = Object::cast_to<SubViewport>(get_child(i));
		if (!c) {
			continue;
		}
		c->notification(p_notification);
	}
}
void SubViewportContainer::input(const Ref<InputEvent> &p_event) {