[llvm] Add regression tests from ConstantData uselist removal (PR #138960)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **May 8, 1:53 AM EDT**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/138960).


https://github.com/llvm/llvm-project/pull/138960