Limit maximum dismiss distance for screenshot/clipboard UI

On large screens, the dismissal animation can take an unusually
long time because it has to travel all the way to the edge of the
screen. This change limits the maximum distance to 400dp (at which
point the view is faded out completely).

Bug: 271456963
Fix: 271456963
Test: manual (visual change)
Change-Id: I2fe06f9bf8aba8cfd92969cc72ccd31e303a352c