Closes https://github.com/ppy/osu/issues/26213.
Reproduction scenario: switch audio track in editor after timeline
loads.
Happens because `beatmap.Value.Track.Length` is 0 immediately after a
track switch, until BASS computes the actual track length on the audio
thread.
Yes this is a hack. No I have no better immediate ideas how to address
this otherwise.
The intention was to give an idea of what the most common velocity of
the beatmap is, but in hindsight, because the "base" velocity is being
set elsewhere this doesn't make sense. It will/should be 1.0x.
Showing this range is still valuable, though.