[FIX] sale_expense: Fix quantity on SOL when re-invoicing an expense

This is a backport of commit https://github.com/odoo/odoo/commit/b48111635b8f273f5a8b26960b110468908ed3c4


from master to 14.0

Currently, when reinvoicing an expense, a SOL with the expense product is
added to the selected SO, but the 'quantity' field remains at 0.
But when adding expense product to SO, we need to change the sales order
price, because it will be charged to the customer in the end.

So in this commit, we set the quantity on the SOL equal to the quantity set
on the expense.

opw-2377511

closes odoo/odoo#62057

Signed-off-by: Anh Thao PHAM <kitan191@users.noreply.github.com>