[FIX] stock_account: empty move valuation

The validation of a stock move without quantity done create an empty
stock valuation layer. This is not a wanted behavior as :
1. it create record without useful information (0 value, 0 remaining
qty, 0 remaining value)
2. The landed cost value is set on a wrong layer in case of complete
backorder.

This commit bypass the valuation process on a move if it is validated
without any quantity.

opw : 2328258

closes odoo/odoo#58770

X-original-commit: 01e21735dbf3ac2fe975323cee2f4bb93e4ca747
Signed-off-by: William Henrotin <Whenrow@users.noreply.github.com>
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>