[llvm] [workflows] Avoid usage of access token in issue-write.yml (PR #94011)

[Tom Stellard via llvm-commits]

tstellar wrote:

> > @tstellar Is there another advantage to having this upstream rather than just documenting somewhere what tokens need to be setup/with what permissions for the workflows to work?
> 
> The advantage for upstream is that it's one less secret for us to maintain.

And also composite actions don't have access to secrets, so if you want to download an artifact in a composite action you need to add an extra parameter for the secret.

https://github.com/llvm/llvm-project/pull/94011