Improve handling of launching translucent occluding activities.

If the window is translucent we don't want to draw a solid color starting view. We also don't want to translate/scale it, since it's transparent.

Bug: 303010980
Test: launch assistant
Flag: com.android.systemui.translucent_occluding_activity_fix
Change-Id: I11e75fe0215ab812d32ccc8aa2758b6fe58d86c3