Hadrian CI builds don't correctly cache cabal folder

Summary

CI builds using Hadrian all inherit from the .validate-hadrian job template which specifies that it wants to cache the cabal-cache directory. However, this directory is never populated with files causing WARNING: cabal-cache: no matching files in the CI job output. The setup phase of ci.sh does try to restore the cabal directory from the cache but this does nothing since the cache is empty. This causes every job to completely reinstall hadrian from scratch.

Make-based builds have a separate cp -Rf $HOME/.cabal cabal-cache in the after-script phase to populate the cached folder.

Steps to reproduce

This can be observed in the CI output of any Hadrian-based job.

Expected behavior

If we cache a certain folder, it should be filled with the appropriate data so that subsequent jobs can reuse it.

Environment

• GHC version used: HEAD