[clang] [analyzer] Discard non-live source frames from the current stack (PR #213779)

[Benedek Kaibas via cfe-commits]

benedekaibas wrote:

> > I could not yet come up with concrete test cases for it since it is hard to mimic the behavior that caused the false positives
> 
> I believe we used to use `creduce` in these cases, though I don't recommend trying to extract a reproducer. We have higher priorities, and the current `main` branch doesn't contain those errors either.

Ohh, I haven't seen this before. I will definitely test it in my free time.

https://github.com/llvm/llvm-project/pull/213779