[clang] [Clang] Avoid transforming lambdas when rebuilding immediate expressions (PR #108693)

[via cfe-commits]

https://github.com/cor3ntin approved this pull request.

I think this makes sense
I added a couple extra pair of eyes to the review so please wait a bit before merging.

In the future, it would be better to push the unrelated parts of the pr in separate NFC commits, for ease of review. Thanks!

https://github.com/llvm/llvm-project/pull/108693