[llvm] [TTI][BPF]: Undo specific transform-preventing passes and add one TTI hook (PR #97073)

[Yingchi Long via llvm-commits]

https://github.com/inclyc commented:

As discussed on https://reviews.llvm.org/D147078, and https://reviews.llvm.org/D147968#4340701. I think the result will not be much different.

https://github.com/llvm/llvm-project/pull/97073