Adjust osu!taiko constant scroll algorithm to match expectations

[Hiviexd]

resolves #28566

my explanation is in the replies but I'll repost here for visibility:

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it seems like the Constant ScrollVisualisationMethod results in a 60BPM scroll speed by default (hence a 4x multiplier existing, which bumped scroll speed to 240 BPM), so adjusting this line to the following would fix this:

-             double multiplier = VisualisationMethod == ScrollVisualisationMethod.Constant ? 4 * Beatmap.Difficulty.SliderMultiplier : 1;
+             double multiplier = VisualisationMethod == ScrollVisualisationMethod.Constant ? (Beatmap.BeatmapInfo.BPM * Beatmap.Difficulty.SliderMultiplier) / 60 : 1;

I've tested the above and on a beatmap with 1.4 base SV and no scroll speed changes, and toggling between Constant and Overlapping ScrollVisualisationMethod results in identical visuals, which should be the expected behavior.

bNNh2eV.mp4

[peppy]

Going to assume you know best here 👍