[llvm] [ci] Don't add more check targets if "check-all" is present (PR #110277)

[Vlad Serebrennikov via llvm-commits]

Endilll wrote:

Can't we do something along the lines of `check-compiler-rt` instead of `check-all`? That would be much simpler than your change.

https://github.com/llvm/llvm-project/pull/110277