Currently, when no workorders are defined for a production, updating its
`product_qty` through the wizard won't update its qty_producing, meaning
that if the production gets validated right afterwards, the total
produced will be the same as prior the update.
This is missleading and unconsistent with how things work when
workorders are involved, since in that case the `qty_producing` of the
production will be updated through the inverse of the workorder's
`qty_producing`.
Also removed the verification on `produced_qty` as it will never be set
before the MO is done, and the wizard can't be accessed at this point.
Part-of: odoo/odoo#142513
clesgow
4ffd1d86e4