[FIX] stock,purchase,mrp: accumulative security days

Usecase to reproduce:
- Set the warehouse as 3 steps receipt
- Put a security delay of 3 days for purchase
- Set a product with a vendor and 1 days as LT
- Replenish with the orderpoint

You expect to have a schedule date for tomorrow that contains all the
product needed in the incoming 4 days.

Currenly the internal transfer from QC -> Stock is for tomorrow (ok).
The transfer from Inpur -> QC is plan for 2 days in the past. (not ok)
The PO date is plan for 5 days in the past. (not ok)

It happens because the system check at each `stock.rule` application if
purchase is part of the route. If it's then it applies the security lead
time. It's a mistake because we should apply it only the first time.

To fix it we directly set it when the orderpoint run and not during
`stock.move` creation.
However for MTO it's not that easy. We don't want to deliver too
early the customer. So we keep applying the delay during the
`stock.move` creation but only when it goes under the warehouse stock
location.

Part-of: odoo/odoo#109640