SAnalogSlider moves slowly when step size is large

SAnalogSlider calculates FastestStepTime by multiplying the step size value by a constant, resulting in high numbers for larger step sizes. This gets lerped from 1 and used as the repeat time, resulting in the slider moving extremely slowly. We'd expect the slider to speed up as the analog stick is held, but that will currently only occur if step size is less than .33.

It seems that the assumption here was that step size would be something close to zero, which makes sense for the default slider range of 0 to 1 but breaks down when using a custom slider range.

1. Create an SAnalogSlider, and set it's range to something larger then default (e.g. 0 to 100) with a larger step size (e.g. 3)
2. Attempt to operate the slider with a gamepad's directional pad, and note that it works as expected (moving 3 units per step, quickly)
3. Attempt to operate the slider with a gamepad's analog stick and note that it moves extremely slowly (multiple seconds per movement)