[clang] [CIR] Reformat Ops to use common `CIR_` prefix and definition traits style (PR #148865)

[Henrich Lauko via cfe-commits]

xlauko wrote:

### Merge activity

* **Jul 15, 4:07 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/148865).


https://github.com/llvm/llvm-project/pull/148865