Do not apply shade blur on transition to shade when dreaming.

Shade blur updates are triggered on shade state changes. In when the
new state is Shade and the device is dreaming, this is actually dream
entry. In this case, we should not apply a blur as it will affect dream
surfaces such as the overlay.

Fixes: 440661063
Test: atest NotificationShadeDepthControllerTest
Flag: com.android.systemui.no_shade_blur_on_dream_start
Change-Id: Ide47c86c04318096f9d391975f70b61f9c17b939