Ticket 47617 - replication changelog trimming setting validation
    
    Bug Description:  The changelog trimming interval setting is not validated.
                      Multiple and invalid values were allowed.  The new interval
                      was also not taking effect until the old timeout completed.
    
    Fix Description:  Add the config attribute to the core schema to addreess
                      the multivalue issue.  Added the setting validation checks,
                      and notify the trimming thread when the interval is changed.
    
                      Also applied these validatations to the changelog compact interval.
    
    https://fedorahosted.org/389/ticket/47617
    
    Reviewed by: nhosoi(Thanks!)