WM mouse pointer tracking: Cleanup after PointerChoreographer refactor

Remove mouse pointer tracking and icon updating logic from WM, now that
the PointerChoreographer refactor is complete and all pointer icon
updates happen directly in input.

Bug: 311416205
Test: build, presubmit
Change-Id: I622e0d116c8570bc1a0880b868aa11b29776a3c1
14 files changed