[llvm] [ci] New script to generate test reports as Buildkite Annotations (PR #113447)

[David Spickett via llvm-commits]

DavidSpickett wrote:

> It also looks like a coworker's libc change went through without issue:

This build must have been done before the first land or while this was reverted, I don't see it attempting to use the script in the log.

https://github.com/llvm/llvm-project/pull/113447