[llvm] [ValueTracking] Take into account whether zero is poison when computing CR for `ct{t,l}z` (PR #122548)

[via llvm-commits]

goldsteinn wrote:

> Motivation? The opt result will not be improved since it has been handled in ConstantRange::ctlz/cttz.

None particularly, was just confused why was getting the inprecise range during some other things. Seems like 0 cost though...

https://github.com/llvm/llvm-project/pull/122548