Skip dream overlay animations when exiting low light

The dream overlay currently does not animate when entering low light
mode, but does animate when exiting it. This CL skips the animations
when leaving low light and going back to the user dream for consistency.

Bug: 260638159
Test: atest DreamOverlayStateControllerTest, atest DreamOverlayContainerViewControllerTest
      manually verified animations on device

Change-Id: Ie097eaeef803cd5d39fa3c8206a2263ca22d5119