When migrating, if the user supplies a subset of the current Realm schema, Core will not automatically delete tables not present in the new schema. Not only that, but it will not delete objects in those tables either. This may be counterintuitive to users as they will expect that by removing a type the file size will decrease. We should expose a mechanics to delete leftover tables similarly to what we're doing in the .NET SDK here: https://github.com/realm/realm-dotnet/blob/6a4e29511ec206a14eee7635c243da963ef0d292/wrappers/src/shared_realm_cs.cpp#L732-L755