Revert "Refine divider behavior"

This reverts commit 50cd6361.
Now resize happens only after the divider is released, so these changes are
no longer needed.

This also fixes resize of 'non-docked' stack in split-screen during dragging
the divider: minimizeHoles was setting incorrect 'taskPositionOther' value
which lead to incorrect insets.

Bug: 27621228
Change-Id: Iec8dc977296e204b206954847dddfc159f498930