Impacted versions: 9.0

Steps to reproduce:

* Create an MTO product with 
  * Product Type: Stockable Product
  * Routes: "Buy" and "Make to Order"
* Update Qty on Hand to any quantity (i.e, 2).
* Create a sales order with this product and a number <= to the one in the step before.
* Confirm the sales order.

Current behavior:

The created delivery picking appears in state "Reserved" and the current quantity on stock has been reserved, allowing you to transfer that stock.

Expected behavior:

The created delivery picking should be in "Waiting another operation", or at least in "Waiting availability" until the purchase order is confirmed (if you have defined a supplier for the product and the procurement creates the purchase order), which seems to be the current behavior when there's no stock available (is this also correct, as it allows to manually reserve?).
'''This function returns quantity of product that needs to be deducted from the orderpoint computed quantity because there's already a procurement created with aim to fulfill it.
        '''
        cr.execute("""select op.id, p.id, p.product_uom, p.product_qty, pt.uom_id, sm.product_qty from procurement_order as p left join stock_move as sm ON sm.procurement_id = p.id,
                                    stock_warehouse_orderpoint op, product_product pp, product_template pt
                                WHERE p.orderpoint_id = op.id AND p.state not in ('done', 'cancel') AND (sm.state IS NULL OR sm.state not in ('draft'))
                                AND pp.id = p.product_id AND pp.product_tmpl_id = pt.id
                                AND op.id IN %s
                                ORDER BY op.id, p.id
                    """, (tuple(orderpoint_ids),))
        results = cr.fetchall()
        current_proc = False
        current_op = False
        uom_obj = self.pool.get("product.uom")
        op_qty = 0
        res = dict.fromkeys(orderpoint_ids, 0.0)
        for move_result in results:
            op = move_result[0]
            if current_op != op:
                if current_op:
                    res[current_op] = op_qty
                current_op = op
                op_qty = 0
            proc = move_result[1]
            if proc != current_proc: