Issue 50474 - Unify result codes for add and modify of repl5 config
    
    Bug Description:
    Same constraints resulting in error are reported as different LDAP
    result codes when using different operation for adjusting these.
    
    Fix Description:
    A part of the code had not conveyed the error reason down the stack,
    therefore adding this information and returning the proper code.
    
    Fixes: https://pagure.io/389-ds-base/issue/50474
    
    Author: Matus Honek <mhonek@redhat.com>
    
    Review by: mreynolds, spichugi (thanks!)
    
    (cherry picked from commit 9bf0fc293b4c0d89f51a3b74fd77d6448c65c02d)