spinbutton: Avoid touch text handles to pop up

spinbutton: Avoid touch text handles to pop up

Those get in the middle more than help on these widgets, the widget
is already packed with clickable areas and having handles (and their
invisible clickable area around) hovering above don't help, plus the
purpose in most likely numeric values is a bit doubtful.

All touch events are either consumed by the up/down panels, or
the swipe gesture, all GtkEntry handling of touch events on the text
window is avoided, so handles to not appear anymore.