If we scroll down in a list that's still being filled, we hit the edge and
initiate overshoot, and then the adjustment's upper value increases. This
leads to an unwanted bounce back.
Additionally, if in a similar situation the upper value decreases, the
overscroll glow gets stuck.
Update kinetic scrolling upper and lower value on changes, and immediately
cancel it if dimensions on that side change.
Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/3752
GtkKineticScrolling implements the actual physics laws for friction
and springs. When created, position/velocity/boundaries/constants are
given, so at every gtk_kinetic_scrolling_tick() it returns the current
position, and whether the system is in rest.
https://bugzilla.gnome.org/show_bug.cgi?id=729608
