[clang] [clang] fix half && bfloat16 convert node expr codegen (PR #89051)

[via cfe-commits]

JinjinLi868 wrote:

> > ok, you mean, i remove the vector testcase for this patch. and just save the scalar testcase?
> 
> No, keep the tests. Only keep the scalar behavior change. The previous revision was essentially correct and minimal

i have changed. just save the scalar on this patch

https://github.com/llvm/llvm-project/pull/89051