[llvm] [IR][unittests] Replace of PointerType::get(Type) with opaque version (NFC) (PR #123621)

[Mats Jun Larsen via llvm-commits]

junlarsen wrote:

> Looks like a unit test is failing.

I accidentally used the wrong renamed variable when I was doing this last night. It should be good to go now.

https://github.com/llvm/llvm-project/pull/123621