[llvm] [memprof] Update YAML traits for writer purposes (PR #118720)

[Florian Hahn via llvm-commits]

fhahn wrote:

Great thanks! Would also be good if you could keep an eye out for build failures from the build bots. I think https://lab.llvm.org/buildbot/#/builders/190 and https://lab.llvm.org/buildbot/#/builders/23/builds/5491 should send emails, Green Dragon unfortunately doesn't at the moment :( 

https://github.com/llvm/llvm-project/pull/118720