Deprecate 2 methods

setQsScrimEnabled does nothing in a scene container context, because
scrim enablement is handled internal to transitions there.

updateSystemUiStateFlags's responsibilities are handed by
SceneContainerPlugin via flow collection rather than pushing flag
updates all over the place.

Flag: NONE
Test: No functional changes
Bug: 303267342
Change-Id: Icc662b533de6962f9bb441f35349eeec990b82a8