[clang] [CIR] Fix CIR tests after recent ABI change (PR #220749)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

> Can we add a ` -fclang-abi-compat=` test here too? It would be great to catch when the ABI flag is enabled that we actually 'revert' this to the old behavior.
> 
> I don't want to approve this until Adam says it is OK howeve.r

I don't feel like I can do that until it's done for classic codegen. The change I made here wouldn't be gated by the ABI compatibility change.

https://github.com/llvm/llvm-project/pull/220749