fix: dropOverItemsCallback when you return to the cell from which you…

[kryshac]

When you drag and drop on a cell that is not empty and you return to the initial position, there is a bug on dropOverItemsCallback, because the last valid position was the current one, the collision is not deleted and dropOverItemsCallback is called on the current position but with the value of to another position.

Below is a gif of how it reproduces:

After fix: