[llvm] Workflows: Use new depot runners for x86 Linux release builds (PR #117111)

[Tom Stellard via llvm-commits]

tstellar wrote:

> Some nits so far.
> 
> It seems like there's a lot of additional complexity from having to support both single stage and multi stage builds? Is it possible to just do single stage builds on depot like we did for the container build?

I agree, but we can't drop the multi-stage builds until we get more powerful mac/Windows runners to use.  I thought about splitting the workflow, but the main reason I didn't is that I thought there would be too much duplication between the two workflows.  I could try to factor out the common stuff and put it in a composite action, and I can do that if you think it will be better.

https://github.com/llvm/llvm-project/pull/117111