Closes https://github.com/ppy/osu/issues/36453.
My omission was in assuming that web was going to start filtering out
the tags below the threshold from API responses, which is not the case.
Whether or not the consumers want or not to display tags below threshold
is subjective. I figured that the matchmaking card tooltip might want to
display below threshold but I dunno.
This is dodgy as hell but `ShortName` is completely derived from
`OnlineID` anyway so there should be no valid reason to ever attempt to
serialise it anyway.
Completely aware that this isn't how it should be done, but would like
to get this out in a hotfix release today. Maybe changes opinions on
https://github.com/ppy/osu/pull/16890 structure?