[FIX] stock: prevent the import of stock.move.line with reserved quantity

Use case: Create an import file for a picking with stock.move.line directly in
it and add some reserved quantity on the stock.move.line.

The import of stock.move.line is not possible directly via a
stock.move.line menu but it still possible on a picking or
mrp.production import. However the create does not expect that
and never reserve the quants. So it result with quant <-> sml
inconcistencies in the data and the error can not reserve more
than you have in stock.

opw-3277938

closes odoo/odoo#119201

Signed-off-by: William Henrotin (whe) <whe@odoo.com>