Stop creating latest symlinks with Pungi
    
    These symlinks are created next to the compose by default, and ODCS
    doesn't use them in any way. It also doesn't delete them, which causes
    accumulation of broken symlinks on the storage.
    
    Where latest symlinks are needed, ODCS handles them by itself.
    
    This is particularly nasty for raw_config composes, where following
    paths can exist:
    
        /mnt/odcs/odcs-395405                  - actual compose directory
        /mnt/odcs/latest-RHEL-8.2              - Pungi created latest symlink
        /mnt/odcs/test/latest-RHEL-8.2.0       - ODCS created latest symlink
        /mnt/odcs/test/RHEL-8.2.0-20200626.t.5 - ODCS created nice symlink
    
    The second item is never going to be cleaned up.
    
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>