### Godot version

v4.1.stable.official [970459615]

### System information

Godot v4.1.stable - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1660 Ti (NVIDIA; 31.0.15.3598) - AMD Ryzen 7 3700X 8-Core Processor (16 Threads)

### Issue description

is_input_handled() is returning True, even though set_input_as_handled() has not been called.

Example:
`func _input_event(viewport, event, shape_idx):
	print(viewport.is_input_handled())`

Returns 'True', should return 'False'

### Steps to reproduce

1. Create a new project and add a Node2D as the root
2. Add a child Area2D node containing a CollisionShape2D and a Sprite2D
3. Either create the _input_event(viewport, event, shape_idx) or connect _on_input_event(viewport, event, shape_idx)
4. Print viewport.is_input_handled()
5. True is printed.

### Minimal reproduction project

[input_test.zip](https://github.com/godotengine/godot/files/12063748/input_test.zip)

if (p_window == nullptr) {
		
		if (gui.subwindow_focused) {
			gui.subwindow_focused->_event_callback(DisplayServer::WINDOW_EVENT_FOCUS_OUT);
			gui.subwindow_focused = nullptr;
			gui.subwindow_drag = SUB_WINDOW_DRAG_DISABLED;
		}
		Window *this_window = Object::cast_to<Window>(this);
		if (this_window) {
			this_window->_event_callback(DisplayServer::WINDOW_EVENT_FOCUS_IN);
		}
		return;
	}
	int index = _sub_window_find(p_window);
	ERR_FAIL_COND(index == -1);
	if (p_window->get_flag(Window::FLAG_NO_FOCUS)) {
		
		if (gui.subwindow_focused) {
			gui.subwindow_focused->_event_callback(DisplayServer::WINDOW_EVENT_FOCUS_OUT);
			gui.subwindow_focused = nullptr;
			gui.subwindow_drag = SUB_WINDOW_DRAG_DISABLED;
		}
		
		SubWindow sw = gui.sub_windows[index];
		gui.sub_windows.remove_at(index);
		gui.sub_windows.push_back(sw);
		_sub_window_update_order();