Fix slider head being incorrectly dimmed twice

[Detze]

Resolves #25761.

Notice that the slider heads's approach circles are also dimmed in the footage in the issue. Slider heads are supposed to behave like hit circles, which dim their body, but not their approach circle.

The issue is that DrawableSlider dims its elements, including its HeadCircle, but DrawableSliderHead, inheriting from DrawableHitCircle, already dims itself (while also not dimming the approach circle), so the slider head is incorrectly being dimmed twice.

Thus, the solution is to remove the slider head from the list of slider elements to dim.

Not sure why it's an issue only most of the time (eg. from a few seconds into the map) and not always. The drawable hit object's state might not always be updating when it should? Either way, the addressed issue is gone now.

some data

In the footage, the cutoff point seems to be between the orange 5 and the orange 6. Times in the map:

• offset: -16
• first hit object: 18734
• orange 5: 20984
• orange 6: 21265

On my test map (offset 676) it would usually happen at 11497, but usually not at 11568.

Sometimes, moving the slider to a new time, or even just seeking away and back, would resolve or reintroduce the issue on the slider, or removing all objects before the tested slider and existing and re-entering the editor would resolve the issue. Changing offset didn't make a difference.

before	after

[bdach]

Not sure why it's an issue only most of the time (eg. from a few seconds into the map) and not always.

There's something else there at play because I noticed when testing this that on some maps the slider tail won't dim correctly when it should. See attached video:

Untitled.mp4

Anyhow I'll look into that separately. This seems fine on its own.

actually hold it, i'll investigate the tail issue first, because i have a feeling we may want to do something else here

[bdach]

Upon further investigation tails not correctly dimming is a separate issue. On first use of every pooled object it would "fix" the double dim of the slider head, but break the single dim of the slider tail.

Working on fix, will be submitted separately.