### 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)

ERR_MAIN_THREAD_GUARD;
	if (gui.subwindow_focused) {
		gui.subwindow_focused->push_text_input(p_text);
		return;
	}
	if (gui.key_focus) {
		gui.key_focus->call("set_text", p_text);
	}
}
Viewport::SubWindowResize Viewport::_sub_window_get_resize_margin(Window *p_subwindow, const Point2 &p_point) {
	if (p_subwindow->get_flag(Window::FLAG_BORDERLESS) || p_subwindow->get_flag(Window::FLAG_RESIZE_DISABLED)) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}
	Rect2i r = Rect2i(p_subwindow->get_position(), p_subwindow->get_size());
	int title_height = p_subwindow->get_theme_constant(SNAME("title_height"));
	r.position.y -= title_height;
	r.size.y += title_height;
	if (r.has_point(p_point)) {
		return SUB_WINDOW_RESIZE_DISABLED; 
	}
	int dist_x = p_point.x < r.position.x ? (p_point.x - r.position.x) : (p_point.x > (r.position.x + r.size.x) ? (p_point.x - (r.position.x + r.size.x)) : 0);
	int dist_y = p_point.y < r.position.y ? (p_point.y - r.position.y) : (p_point.y > (r.position.y + r.size.y) ? (p_point.y - (r.position.y + r.size.y)) : 0);
	int limit = p_subwindow->get_theme_constant(SNAME("resize_margin"));
	if (ABS(dist_x) > limit) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}