[clang] [Clang] Fix failing CI with different test case attribute & test macro (PR #76863)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

Looks fine to me, triple of x86_64 + gnu should be enough to make sure this is a supported attribute.

https://github.com/llvm/llvm-project/pull/76863