Break tiling on entering pip mode.

When entering tiling, an app changes mode from freeform to pinned, and
this breaks tiling.

This CL removes the app from tiling on entering PIP mode.

Flag: com.android.window.flags.enable_tile_resizing

Test: on device testing of UI, really hard to unit test the UI here.

Bug: 397663717
Change-Id: I4b8b7afa416eb3599dfc566e207449e6eaa343cc