Set the surface to be opaque when blur is not supported and shade is fully expanded.

This prevents the surface below from becoming visible when blur radius drops to 0

Bug: 405288154
Test: verified all CUJs manually with bouncer blur enabled and shade blur flag enabled and disabled
Test: with shade and bouncer blur enabled, pull down shade and enable/disable battery saver repeatedly, surface below should not be visible when battery saver is enabled
Flag: com.android.systemui.bouncer_ui_revamp

Change-Id: I3b4ebde11d3138c3c06088ade97ebcee9305e258