Related: https://github.com/ppy/osu/issues/30539
When starting up the game with a data location that points to an
unavailable external device, a new realm file is created in the default
location. Eventually a popup is shown that informs the user that the
external storage is unavailable, and the user has an option to try the
storage again. The button that invokes said option would check said
storage correctly, but would not do anything about realm, which means
the previously opened empty realm that is placed in the default location
would remain open, which means the retry essentially doesn't work
because the user's stuff isn't there after the retry.
To fix this, take out a `BlockAllOperations()`, which will flush all
open realms, and re-open the realm on the external location if the
custom storage restore succeeds.