Adaptively call wiredtiger_calc_modify

When updating in wiredtiger record store, wiredtiger_calc_modify is called to attempt to get a diff for faster update. However, when it fails to calculate such a diff, the time goes wasted. For certain workload (e.g. time series), we found that the calculation rarely succeeds and slows down the updates. We would like to implement a general heuristic (not just for time series) to adaptively increase or decrease the frequency on attempting to do the calculation.

After implementing the heuristic, the "engineering solution" for time-series in the linked ticket should be removed.