Replace @RequiresFlagsDisabled with @DisableFlags

For some unknown reason the former was unsuccessful in skipping the test
when the flag is enabled.

Bug: 370555223
Flag: com.android.systemui.notification_shade_blur
Test: atest NotificationShadeDepthControllerTest

Change-Id: Iff9a3a23f6fa1788157dcbbbcb5b5a275de6159f