Ticket 47383 - connections attribute in cn=snmp,cn=monitor is counted twice
    
    Bug Description:  In disconnect_server_nomutex() we increment, instead of decrement
                      the connection counter.
    
    Fix Description:  Decrement the counter.  Also did some code cleanup.
    
    https://fedorahosted.org/389/ticket/47383
    
    Reviewed by: Richm(Thanks!)
    (cherry picked from commit 202c9831194558a7439da815f6627993ce1a17db)