The tests were relying on the `RulesetID` being set to 0 in the example
beatmap, even though the ruleset *instance* was set to ID 5.
This explicitly adds that 0 value to show intent, and also removes the
incorrect specification of 5 (which would cause the convert filter tests
to fail).
Also updates the filter code to use `OnlineID`, which is required in
realm changes.
These can be tested by adding a `Task.Delay(3000);` at the end of the
`MultiplayerClient.JoinRoom` task. The reason is typically that
`Client.Room` becomes not-null but the join task still hasn't completed
yet, so e.g. the ready button is still disabled.