Fix Fedora 39 branching
    
    Ensure that both release & update repos are enabled. Only the release
    repo will be populated in the Fedora infra for now but this avoids
    downgrades once we enable updates for F39.
    
    Remove the now unused Rawhide repo.
    
    Keep the README as is.
    
    Fixes: fd05565 this is f39 branch, switch from rawhide