Fix `SongProgress` invalidating too often
Fix `SongProgress` invalidating too often

This regressed with https://github.com/ppy/osu/pull/19556. Rather than
try and figure whether that new container needs to handle size
differently, this is a simple solution.

Height was taken from a runtime check (maxes out at about 14.5).

Closes #20235.

ppy/osu,peppy/osu,peppy/osu,ppy/osu,ppy/osu,peppy/osu