block_retired: Block packages which are not active in PDC
    
    This is opposite to what was happening, we were blocking packages which
    are not active... But some packages might not even be recorded in PDC
    for specific branch.
    
    Let's just do opposite, find all unblocked packages in Koji, all active
    packages in PDC and block what is not in the list.
    
    Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>