I have created a new differential that actually exposes the "CleanAux" setting in the user interface. D12099: Cycles-X: Expose "CleanAux" setting in the UI

In a recent commit that made changes to Cycles-X to accommodate new features from OIDN 1.4.X, the "CleanAux" setting was enabled for all use cases. This has lead to some confusion in some users and can lead to some artifacts when "Prefiltering" is turned off, which a user may wish to do for performance reasons.

I would love to create a diff that makes "CleanAux" and "Prefiltering" separate options, but I'm not well versed in programming so this is the best I can do (looking at someone else's code (https://developer.blender.org/D12043?vs=40066&id=40129), copying it, compiling to make sure it doesn't break anything, testing it, then publishing).