[llvm] [Workflows] Re-write release-binaries workflow (PR #89521)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 approved this pull request.

Overall LGTM.

Do you have numbers on how much time this ends up saving on the larger runners?

Hopefully soonish (might be a while) we have sufficient self-hosted runners where we can run these jobs so we don't have to add the complexity of splitting. Nice to see that this idea seems to work out in practice though!

https://github.com/llvm/llvm-project/pull/89521