[clang] [NFC][analyzer] Eliminate SwitchNodeBuilder (PR #188096)

[Balázs Benics via cfe-commits]

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

I still didn't spot any mistakes. However, I think that you found one subtle error, we should move carefully here.
Did you run it on the bench? If not, please consider giving it a run before merging.

https://github.com/llvm/llvm-project/pull/188096