Adjust "classic" mod multiplier to 0.96x

[peppy]

Following discussions on discord, this seems like the most agreed upon value. Increasing this is important so that imported legacy scores don't lose too much value.

[bdach]

Just to confirm because I didn't realise this last time for whatever reason (good reviewing me, well done):

This is applied at ModClassic level, so this means that the 0.96x multiplier will hold across all rulesets, not just osu!. And most arguments for multiplier concerned slider head accuracy, which is an osu!-specific concern.

In light of that, are we confident that the placement of this multiplier is correct?

[peppy]

I think across all rulesets is best for the initial release. We can tweak as required, once we have leaderboards to work with.

[april83c]

What if the multiplier was different depending on which options of the Classic mod you actually have selected — e.g. if you disable "No slider head accuracy requirement"?