Issue 51100 - Correct numSubordinates value for cn=monitor
    
    Bug Description: numSubordinates for cn=monitor shows 4
    while there are 3 child entries are present.
    
    Fix Description: Ignore easter egg entry while increasing
    numSubordinates count.
    
    https://pagure.io/389-ds-base/issue/51100
    
    Reviewed by: mreynolds (Thanks!)