[FIX] stock: quantity done not saved on pager
[FIX] stock: quantity done not saved on pager

On delivery order, it happens that when it contains more than 40
products and multiple pager. The quantity done are only saved on
the first pager and on the other everythings is reset to 0.
This issue is not deterministic.

The reason is because on the picking view, both stock.move and
stock.move.line are present. When the user write the quantity done
on a stock.move it exists a function inverse that write qty_done on
stock.move.line. However during an onchange, inverse function are not
trigger and every field present in the view is returned to the client.
It means that data after the onchange are inconsistent since the
quantity done write on the move is different than the quantity on the
move line. When the user save the form view, the write could be trigger
in different order. If the write on stock.move is trigger first, it will
write the qty_done with the inverse function but it will be erase by the
write on stock.move.line that is trigger after.

In order to fix it, we set the stock.move.line as readonly when they are
not needed, so they are not send to the server.

closes odoo/odoo#27903
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo