Revert "fedora.conf: Remove deprecated option in ostree(_installer) phases"
    
    This reverts commit b7eaa146822662e3be4a60d38f4ec5c085532e81.
    
    This is still needed in validation for now. Lets put it back and only
    remove it once it's actually removed in pungi schema.
    
    Signed-off-by: Kevin 'sign offs are stupid' Fenzi <kevin@scrye.com>