Ticket 48989 - fix perf counters
    
    Description:  There was a copy & paste error where page_access_rate
                  was added, but it listed the wrong attribute name.  However,
                  the page_access_rate formula doesn't make sense, nor are
                  there more page stats to use from Berklely DB.  Because
                  of this I just removed page_access_rate.
    
    https://pagure.io/389-ds-base/issue/48989
    
    Reviewed by: firstyear(Thanks!)
    
    (cherry picked from commit 18a77e957119bd9994833b7290747f99d73b3745)