Rely on builder-debian doing it. This way it will be reproducible.

QubesOS/qubes-issues#2775

Xorg does some not accurate calculations and values above certain point
have fraction parts (like 15999.98 instead of 16000).

Emulating tablet device requires specified precision - which is not
supported by python-uinput. Otherwise Xorg refuse to use it as tablet.
On the other hand, touchscreen does not require it, but also udevd in
Fedora >= 28 require that touchscreen has no mouse buttons, otherwise it
tags it as a mouse.

To work with that, modify tablet events to include only BTN_TOUCH.

Click far from the screen edge, to avoid opening menu, which can
interfere with further tests.