[llvm-branch-commits] [CI] Migrate to runtimes build (PR #142696)

[Aiden Grossman via llvm-branch-commits]

boomanaiden154 wrote:

This/dependent patches are intended to land after we deprecate/shutdown Buildkite. No effort was made here to keep the Buildkite pipeline working in the same manner as the Github workflow.

https://github.com/llvm/llvm-project/pull/142696