Remove all calls to Realm.Refresh to fix blocking overhead from subscriptions

Turns out this is not required if realm is aware of a
`SynchronizationContext`. See
https://github.com/realm/realm-dotnet/discussions/2775#discussioncomment-2005412
for further reading.

osu.Game/Database/EFToRealmMigrator.cs

@@ -46,9 +46,6 @@ namespace osu.Game.Database
                 migrateScores(ef);
             }
 
-            Logger.Log("Refreshing realm...", LoggingTarget.Database);
-            realmContextFactory.Refresh();
-
             // Delete the database permanently.
             // Will cause future startups to not attempt migration.
             Logger.Log("Migration successful, deleting EF database", LoggingTarget.Database);