Before the introduction of `StoryboardResourceLookupStore`, missing
files would softly fail by use of null fallbacks. After the
aforementioned class was added, however, the fallbacks would not work
anymore if for whatever reason `GetStoragePathFromStoryboardPath()`
failed to unmap the storyboard asset name to a storage path.
Closes https://github.com/ppy/osu/issues/22802.
Stable uses a 1,000 ms fade-in / out. Rather than matching that, I've
stuck with 500ms (what lazer was already using for the fade-in) because
I think it feels better.
Tested using the beatmap linked in the issue thread.