[llvm] [NFC][LLVM] Remove unused `TargetIntrinsicInfo` class (PR #126003)

[Reid Kleckner via llvm-commits]

https://github.com/rnk approved this pull request.

I think we can remove this with a release note update. I think as far as disruptive C++ API update changes go, this is pretty minor. The intrinsic files today are more pluggable than they were when this interface was conceived.

https://github.com/llvm/llvm-project/pull/126003