[llvm] workflows: Fixes for building the release binaries (PR #83694)

[Tom Stellard via llvm-commits]

tstellar wrote:

> LGTM.
> 
> I'm wondering if we can set this up to trigger on dependency workflow/actions changing like we've done with other jobs to catch regressions earlier. It might need some restructuring though with the permissions check.
> 

I can look into this.

> I'm also wondering if we're able to get rid of the cache filling stage now that double the cores are available on the free runners? Might reduce some complexity that isn't needed now.
> 

The free runners still aren't powerful enough to do the release builds in less than 6 hours, so we have to keep using the non-free builders for this.  The cache filling stage sill saves us money, so I think we have to keep it.


https://github.com/llvm/llvm-project/pull/83694