Performance: Do not request count-numbers when only resorting

Two adjacent issuelist data-requests, when the only change in the request is in the sorting parameters, don't need to request count number (totalRowCount, totalAddedCount, totalRemovedCount) via the parameter computeTotalRowCount=true, because the count values won't change from the first to the second request. This should speed up responses as the server does not need to issues one or several "SELECT COUNT() .."-queries to compute those numbers.