Remove duplicate bouncer blur in dream overlay

When bouncer revamp is enabled, the bouncer will handle blurring the
dream. We don't need this dream-specific blur logic.

Flag: com.android.systemui.bouncer_ui_revamp
Bug: 394641076
Test: atest DreamOverlayContainerViewControllerTest
Change-Id: I2760e3012382bf692fcf6c469974c1c50ca49da2