Deprecate PipBoundsHandler#mLastDestinationBounds.

It's only used in one place, and just for setShelfHeight. We will just
use PipTaskOrganizer's bounds instead.

Bug: 147155783
Test: atest PinnedStackTests
Change-Id: I3a200a5df65e4e602286e9397b3b4586f9c2952f
2 files changed