[llvm] [mlir] [OMPIRBuilder] Don't outline DISTRIBUTE on CPUs (PR #158317)

[Tom Eccles via llvm-commits]

tblah wrote:

Failing Windows test is unrelated:
```
2025-09-23T09:46:28.8736279Z Failed Tests (1):
2025-09-23T09:46:28.8736470Z   lld :: wasm/lto/thinlto.ll
```

https://github.com/llvm/llvm-project/pull/158317