Ticket 49461 - Improve db2index handling for test 49290
    
    Bug Description:  db2index has limited parameters we can accept,
    including the types of attributes we can index. Specificatlly,
    we must take an index name, else we do not re-index (look at
    ns-slapd, we require -t or -T, and if we do, we require them
    to have a value.
    
    Fix Description:  Fix lib389 to match the assertions of ns-slapd
    with regard to db2index behaviour.
    
    https://pagure.io/389-ds-base/issue/49461
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)