(ITS#9119) back-monitor can miscount monitorOpCompleted

Full_Name: Quanah Gibson-Mount Version: 2.4.43 OS: N/A URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (47.208.143.26)

When querying the monitor backend for monitorOpCompleted, the results are inconsistent. The code that calculates this value is also inefficient, as there is already a global counter of completed operations, but back-monitor doesn't use this and instead queries all the per-operation counters and then sums them together for the result, causing unnecessary work.

These are the results of a series of queries:

monitorOpCompleted: 326801 monitorOpCompleted: 326733 monitorOpCompleted: 326830 monitorOpCompleted: 326830 monitorOpCompleted: 326752 monitorOpCompleted: 326855 monitorOpCompleted: 326777