Test util for shade that accounts for flag values

The util sets up state regardless of the value of the scene container
flags. This change also removes some redundant tests, moves one test
to the correct class, and deletes some dead code.

Bug: 334874076
Test: ran affected tests
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Change-Id: I7e5e5f50fed79682f14e500442c3ef2411df1214