[TTI][X86] getMinMaxCost - use existing integer min/max intrinsic cost values...

[TTI][X86] getMinMaxCost - use existing integer min/max intrinsic cost values instead of maintaining a duplicate cost table

getMinMaxCost has an alternative set of min/max costs to getIntrinsicInstrCost that are only used by getMinMaxReductionCost, but are a lot less thorough and fallback to an expansion in most cases resulting in cost overestimations - we're better off just using getIntrinsicInstrCost.

getIntrinsicInstrCost is still missing complete FMINNUM/FMAXNUM costs, so until then getMinMaxCost will still be used for these, after that we can remove getMinMaxCost and have getMinMaxReductionCost call getIntrinsicInstrCost directly.

Fixes regression noticed in D148036