Turn off generic multi-window and multi-display.

This was used for an Activity in a virtual display as an alternative to ActivityView on O/G, but now that ActivityView is back it is the preferred approach.

Bug: 111277046
Change-Id: I0b1ca1826d487bec321cb5bed80ca79600c6bced
(cherry picked from commit 438d0077373a5bfdcd628f4f081cb7ee5f87f929)