Fix pip window can't move in recents

Just place the pip input consumer at the top display area instead of
the root task, or the recents input consumer would take all touch for
it's already put to the top of the display area.

Test: enabled pip, enter recents from app, move pip
Bug: 231419738
Change-Id: I15d765c01ebd541ee247ff12cbb3775b42ea3307