[SB][Flexi] Hide home status bar on lockscreen when flexiglass enabled.

Fixes: 342107016
Flag: com.android.systemui.scene_container

Test: Disable flexiglass -> status bar smoke test
Test: Enable flexiglass -> setup screen lock, unlock device, then
relock -> verify home status bar doesn't appear on lockscreen
Test: Enable flexiglass -> on lockscreen, trigger occluding activity ->
verify home status bar appears
Test: atest CollapsedStatusBarViewModelImplTest
CollapsedStatusBarFragmentTest

Change-Id: I3c1e21e6538e146ac4e0595e99b84b1b0f951f78