[llvm] Make sure all matrix options are run in libc premerge testing (PR #146162)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

If we want to just land this as a stop-gap without being more principled about the configurations we're testing, we might want to hold off until we've moved over to Github Enterprise. This workflow now uses 25 jobs out of our maximum concurrent of 60, and given lots of other things that are expected to normally be pretty quick (issue labelling) also count against the cap and will queue, this might degrade the UX a bit.

https://github.com/llvm/llvm-project/pull/146162