Revert "X11 backend: don't set TouchpadOff to 1"

This reverts commit d88c8ab68a4e7efff5fbccaa6c203d3570217b44.
Set "TouchpadOff" and "Device Enabled" properties separately

"Device Enabled" is used to manually disable touchpad.
"TouchpadOff" is used to disable touchpad while typing.

This should improve compatibility with ktouchpadenabler.
Also, it simplifies kded logic.

BUG: 331285