Fix recents attached state when quick switching

Don't wait for drag slop before determining whether we are likely
to quick switch (xDisplacement > yDisplacement). One glaring issue
is that we only pass drag slop when swiping up, not sideways...
so to pass drag slop going sideways we actually had to pass touch
slop (24dp vs 10dp) and by that point the adjacent task was probably
visible if you swiped fast, and thus we faded it in. Now we only
look at raw displacement for purposes of determining whether we are
likelyToStartNewTask, which should be much more consistent.

Bug: 129985827
Change-Id: I31f8a9830681851093de2ce159da1a1dc4f7ef6a