Fix mods from single player carrying over to multiplayer
The test was checking the test scene's own `SelectedMods` bindable rather than the multiplayer screen's, and the former was never actually being mutated by anything. Therefore the case would pass even on `master` with the fix reverted.
TestSceneScreenNavigation
As seen at https://github.com/ppy/osu/runs/5492345983?check_suite_focus=true.
DialogOverlay
Apparently the previous fix was not enough as this can still be seen failing (https://github.com/ppy/osu/runs/5046718623?check_suite_focus=true). This change is copying from what other tests use seemingly reliably, such as `TestScenePerformFromScreen`)
As seen at https://github.com/ppy/osu/runs/4999391205?check_suite_focus=true, where `DialogOverlay` hasn't loaded in single file yet.
Wait
WaitSafely
BeatmapSetInfo
Metadata
There were very few accesses to this, and after realm they should all be done via the `BeatmapInfo`, so let's remove this.
TestMultiplayerScreenStack
TestMultiplayerComponents
RulesetInfo
OnlineID
ID
IWorkingBeatmap
TestOverlayClosing
OsuGame