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)