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

[David Spickett via llvm-commits]

DavidSpickett wrote:

I'm away next week so feel free to merge this yourselves (if it looks good) or write your own version (if it doesn't). If I'm right it'll be a nice saving.

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