Shoulder rotating back math is inconsistent with VRIK

[sclark39]

While determining if the shoulder should be rotated back towards the hand, 0.08 is the distanceRatioThreshold. To create an area about 0 which has no rotation, within the range [-0.08, 0.5] it should be adding 0.08 not subtracting (since ForwardDistanceRatio is negative here). https://github.com/JonasMolgaard/UBIKSolver/blob/acc72b60b03ea22c44aaa474e01c26653f156331/Source/UBIKRuntime/Private/AnimNode_UBIKSolver.cpp#L435

(As an aside, VRIK actually had its own bug in this section but because the default back shoulder limit was 0, it didn't matter.)