Fully disable SCM when users pick fullscreen in settings

Prevent an app from entering SCM on fold/unfold transitions or in
multi-window mode.

Fix: 308739958
Test: atest WmTests:SizeCompatTests#testShouldCreateCompatDisplayUserAspectRatioFullscreenOverride
atest WmTests:LetterboxUiControllerTest

Change-Id: If69b85bf1f0f2a4853a3cdc34c18562ab519d172