[clang] [CIR] Fix dominance problems with values defined in cleanup scopes (PR #183810)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

@Andres-Salamanca I had to make extensive changes to the coroutine test because of some scope changes. Can you look at that and verify that it's still doing what you'd expect?

https://github.com/llvm/llvm-project/pull/183810