[InlineCost] CallAnalyzer: use TTI info for extractvalue - they are free (PR50099)

It seems incorrect to use TTI data in some places,
and override it in others. In this case, TTI says
that `extractvalue` are free, yet we bill them.

While this doesn't address https://bugs.llvm.org/show_bug.cgi?id=50099 yet,
it reduces the cost from 55 to 50 while the threshold is 45.

Differential Revision: https://reviews.llvm.org/D101228