Use RootTaskDisplayAreaOrganizer to change windowing mode

In core, windowing mode is being set in TDA with ag/19902621. Thus, set
windowing mode with RooTaskDisplayAreaOrganizer instead of
RootDisplayAreaOrganizer.

Bug: b/241168290
Test: services/tests/wmtests
Change-Id: Ib7e6701839f83ab4125a9630d20203f8c5e415ba
4 files changed