[ci][ez] Rename artifact from process_artifacts_combined

Build artifacts are uniquely associated to a single workflow run, so appending the sha was unnecessary. I originally included it to make it easier to download later but this turns out to be unneeded. Drops the sha suffix to make downloading the artifact in a separate script / workflow more straightforward. ghstack-source-id: 36ac4df4c35409fd08fbfa8714043eb556ff88d3 Pull Request resolved: https://github.com/facebook/react/pull/30364