The "People with access" list in the page share modal used
<ScrollArea mah={250}>, which caps the container height but does not
make the inner viewport scroll (no fixed height is given to the
viewport). Items beyond ~4 entries were rendered correctly but clipped
out of view.
Switches to <ScrollArea.Autosize mah={400}>, which is Mantine's
dedicated primitive for "grow with content up to a max, then scroll".
Closes#2135
Olivier Lambert
Philip Okugbe