Remove blur from power menu

These were reminiscent from Q style and should not be part of the new
design language.

Fixes: 191736895
Test: manual
Test: atest GlobalActionsDialogLiteTest
Test: atest GlobalActionsDialogTest
Test: atest NotificationShadeDepthControllerTest
Change-Id: I047be8271c1ceff0749450a89eefe16bb07c2b0f