[CopyJob] Report results after finishing copy

Currently, slotReport is called all the way at the end when in STATE_SETTING_DIR_ATTRIBUTES. However, slotReport does nothing in this state.
Instead, move it to before changing away from STATE_COPYING_FILES so that progress is correctly reported for a final time.

BUG: 407656

Differential Revision: https://phabricator.kde.org/D19585