It's all a bit weird so let's just disable it for now. For instance, this is exposed as "text" font / colour but only affects the header. Also, no other headers are cusotmisable in similar components.
- First step for https://github.com/ppy/osu/issues/22087 - Supersedes / closes https://github.com/ppy/osu/pull/22795 Roughly uses design shown in https://github.com/ppy/osu/pull/22795#issuecomment-1579936284 with some modifications to better fit everything else, and some customisation options so it can fit better on other skins.