[clang] [CIR] Run callconv lowering in the tests that opted out of it (PR #216396)

[Adam Smith via cfe-commits]

adams381 wrote:

@erichkeane That is correct.  The tests weren't written to test calling convention lowering, they just happened to use something that reported `errorNYI` by the pass.

https://github.com/llvm/llvm-project/pull/216396