Flickering with DragOverlay after drop animation finished

[medihack]

When using DragOverlay with React in concurrent mode, the dragged item inside the overlay just shows up again for some milliseconds, where it was released after the drop animation. This screencast demonstrates this problem:

I am absolutely aware that concurrent mode is experimental, but I think it justs demasks an already existing problem. Because after the drop animation finished, it seems that the dragged node in the overlay gets its previous transform back (where it was released from). In React legacy mode, it doesn't matter as the DOM is not updated fast enough, but in concurrent mode, the node in the overlay shows up for some milliseconds where it was released before the overlay itself is removed.

A possible fix is to hide the dragged node in the overlay after the drag animation is finished. It will be recreated on the next drag anyway. I'll create a PR if you are ok with this.