Fixing RunService Lerp Jitter

[Yusamika (Abbie)]

@Hajimalago

We believe that Adaptive Timestepping may be advantageous for many of you, offering performance enhancements without jeopardizing the quality of the simulation. However, for those whose projects require the precise physical behavior of full 240Hz simulations, we have ensured that the Fixed option remains available to you.

Fixed timestepping will not be removed.