Change all apps caret target bounding box

b/30400751

1) This also fixes the issue of apps drawer sliding up when page is swiped
horizontally immediately above the hotseat area.

2) Disclaimer: this should be cp'ed to calgary.
Hence, I tried to keep the diff small. Ideally, CaretDrawable animation
handling should move to AllAppsHandleImageView via refactoring in
follow up CL.

Change-Id: I4d808ee2eeca53b40c0b4e4e0e364fef056e26c3