User plugin: do not return the SID on user creation
    
    The SID is not part of the default user attributes and does not
    need to be returned in the user-add output.
    
    Related: https://pagure.io/freeipa/issue/8995
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>