[clang] [CIR][NFC] Simplify BoolAttr builders (PR #136366)

[Henrich Lauko via cfe-commits]

xlauko wrote:

### Merge activity

* **Apr 21, 3:06 AM EDT**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/136366).


https://github.com/llvm/llvm-project/pull/136366