[roll] Roll fuchsia [scenic] Release images while the display is powered off

While the display is off no vsync arrives, so release fences waiting in
ReleaseFenceManager never signal and DefaultFrameScheduler drops every
later frame as "still in flight". Session teardown frames are among the
dropped ones, so dead sessions kept their images and sysmem buffer
collections pinned until the display came back.

- On kOff: drop unacknowledged configs, mark all frames presented.
- On kOff: commit the empty-scene (black) layer for power-on to show.
- Late vsyncs from a dark display log at INFO.
- ReleaseFenceManager: MarkAllFramesPresented().
- DefaultFrameScheduler: ForceRenderFrame(), used at power-on.
- App: frames while dark go through Engine::SkipRender().

Original-Original-Bug: 563046716
Test: flatland_engine_unittests, scheduling_unittests, display_unittests
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1833550
Original-Original-Revision: 9e5288a76d658dddb9853055062243a684909925
GitOrigin-RevId: 819657bebf41fc25ea0f484d43a34c21e9b9c6b6
Change-Id: I5701e1fb82f1220cc27f1db6b585052c34ae1820
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1837124
Cr-Commit-Position: refs/heads/main@{#202536}