Rework SVE predicate variants to re-use x64 code

[a74nh]

Predicate variants for Arm64 SVE were added in #117313

We should rework this to reuse the x64 code where possible.

This is blocked on #118579, enabling constant folding for SVE

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[a74nh]

Setting this to .NET 11 as it's fairly easy to do once #118579 is completed