[clang] [CIR] Refactor IntType constraints (PR #138106)

[Henrich Lauko via cfe-commits]

xlauko wrote:

### Merge activity

* **May 2, 3:15 AM EDT**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/138106).


https://github.com/llvm/llvm-project/pull/138106