QTableWidget: moving rows deletes rows

commit a9e464119a8008d9b1464bf81fad2537954ba739 (https://codereview.qt-project.org/c/qt/qtbase/+/581090)
(which landed after 6.8.0-beta4) turned out to have a nasty bug. At some point during the review process I removed d->dropEventMoved = true; and as a result, moving a row in a QTableWidget deletes a row at the end of the move.

Please include the fix in Qt 6.8.0.