Ticket 49157 -  ds-logpipe.py crashes for non-existing users
    
    Description:  Remove all "raises", and gracefully exit with a message
    
    https://pagure.io/389-ds-base/issue/49157
    
    Reviewed by: firstyear(Thanks!)
    
    (cherry picked from commit 94ebab36770465a50e3f61590f0f1adec2cc9224)