Fix for shade transparency bug when bouncer_ui_revamp flag is not enabled.

This is required for devices that have shade blur enabled but bouncer blur disabled in the trunkfood 50 population.

Bug: 405288154
Test: disable bouncer_ui_revamp, enable/disable battery saver repeatedly
Flag: com.android.systemui.notification_shade_blur
Change-Id: Ie62c35fbe3eec1240c9fff9ff6034c5402bfa0cd