[llvm] Run pre-merge build with -k 0 to ensure all tests runs (PR #84828)

[Tom Stellard via llvm-commits]

https://github.com/tstellar commented:

This seems like a good solution. How does this behave if a file in lib/Support fails to build, will it still try to run the all the tests?

https://github.com/llvm/llvm-project/pull/84828