Fix preference animations when expressive design is off.

Modify SettingsPreferenceGroupAdapter to not impact things when its used
while expressive design is off. Safety Center (and I think Settings app)
currently use this adapter whether or not expressive design is enabled,
and the class already has some handling for that case.

Bug: 382425714
Test: manual and treehugger
Flag: com.android.settingslib.widget.theme.flags.is_expressive_design_enabled
Change-Id: I72846a75ef3adc9d16147fd3daff5b18c3d8c92a