[frontend] remove a redundant condition for outdated chroots
    
    The fact, that some chroot is considered to be outdated (i.e. returned
    by `Copr.outdated_chroots`) literaly means, that it has `delete_after`
    set and therefore even `delete_after_days` can be calculated.
    
    This condition is rather redundant. If not, please revert this commit
    and **document** the scenario.