[FIX] anglo_saxon_dropshipping: fix accounting entries creating on anglo_saxon...

[FIX] anglo_saxon_dropshipping: fix accounting entries creating on anglo_saxon + real_time + dropship.

This revert the fix made on 7bdd4de8 and replace it with a proper one that do create an account entry from stock_input to stock_output on a dropship move. That way, we avoid the manual change of account on supplier invoice. See the whole discussion on odoo#12687