Fixes#8881
The actual issue is that the ViewModel migration actually differs between what the current `init` block
and previous `onSave` methods did; where the `init` block does not get triggered on saving the
instance on config changes.
Not entirely sure why onSaveInstanceState was explicitly avoided for config changes before, but we
just do it all the time now and end up updating the requestedPage with the current page.
(cherry picked from commit 2ebc8d9ae51f84b0f69dee603a5448a72013f734)
# Conflicts:
# app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt
4ee66f6185