nightly.sh: don't sync ostree content
    
    Let's do this in new-updates-sync [1] from now on.
    
    [1] https://infrastructure.fedoraproject.org/cgit/ansible.git/tree/roles/bodhi2/backend/files/new-updates-sync
    
    Signed-off-by: Dusty Mabe <dusty@dustymabe.com>