[llvm] [workflows] Fix lldb-tests and libclc-tests (PR #80751)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

Do you have a failure example? I'm struggling to understand why exactly this failed. I would think that passing a null string to ninja would just cause it to build all rather than failing.

If we want to actually run the tests (which seems to be the intention here?) I think we need to run the `check-*` target, which I assume would be `check-lldb` and `check-libclc` (although not certain on those).

https://github.com/llvm/llvm-project/pull/80751