[llvm] [Dexter] Extend XFAIL of Dexter tests to all MacOS architectures. (PR #83936)

[Jonas Devlieghere via llvm-commits]

JDevlieghere wrote:

GreenDragon is currently down and I have no ETA on when it'll be back up. In the meantime, I setup a new node somehow the tests are now failing there too. I suspect they might not be passing for good reasons on the existing Intel bot so let's disable them 👍

https://github.com/llvm/llvm-project/pull/83936