[llvm] [IR] Do not set `none` for function uwtable (PR #93387)

[Joshua Cao via llvm-commits]

caojoshua wrote:

[IREE sets a None uwtable kind](https://github.com/iree-org/iree/blob/9e3d27ace8349b8875cae6d34450041f1f334122/compiler/plugins/target/LLVMCPU/internal/EmbeddedLinkerTool.cpp#L82). Then when printing LLVM IR with `--print-after-all`, I get

```
Unknown attribute
UNREACHABLE executed at /home/josh/src/iree/third_party/llvm-project/llvm/lib/IR/Attributes.cpp:643!
```

https://github.com/llvm/llvm-project/pull/93387