upgrade: treat duplicate entry when updating as not an error
    
    When we attempt to update an entry during upgrade, it may have already
    contain the data in question between the check and the update. Ignore
    the change in this case and record it in the log.
    
    Fixes: https://pagure.io/freeipa/issue/7450
    (cherry picked from commit 52c0d8c5bfc4d0c1fe8d8318edbf5909d139178c)
    
    Reviewed-By: Christian Heimes <cheimes@redhat.com>