not all the InputEventScreenTouch events is triggered in _gui_input

[alexzheng]

**Godot version:3.1

OS/device including version:

Issue description:

Touch two or more fingers on the screen, two InputEventScreenTouch events is triggered with event.pressed = true, However, when release the fingers, only the last finger triggered a event with event.index =0 , event.pressed = false, all other InputEventScreenTouch events is lost.

In _input function, all these events can get.

Steps to reproduce:

Minimal reproduction project:

[PonasKovas]

Can reproduce.

$ godot --version
3.2.1.stable.official

[PonasKovas]

minimal reproducible example:
inputeventscreentouch.zip

[madmiraal]

Closing as it's a duplicate of #29525.