**Description of the issue/feature this PR addresses:**

When a batch recompute of `vies_valid` contains both a parent (commercial) partner and a child sharing the same VAT, and the child happens to be iterated before its parent, the child ends up with `vies_valid=False` instead of the parent's real, freshly-checked value.

**Current behavior before PR:**

`_compute_vies_valid` loops over `self` in whatever order the batch happens to have:

```python
for partner in self:
    ...
    if partner.parent_id and partner.parent_id.vies_vat_to_check == partner.vies_vat_to_check:
        partner.vies_valid = partner.parent_id.vies_valid
        continue
    status = partner._check_vies_iap()
    partner._update_vies_status(status)
```

`Field.compute_value()` removes the whole batch from the "to compute" queue *before* running this loop (it does so upfront, in case the method does not assign every record). So when the loop reaches a child and reads `partner.parent_id.vies_valid` to reuse it, that field is no longer marked "to compute" for the parent, and reading it just returns whatever is currently cached/stored — which, if the parent has not been processed yet in this same loop, is still the old/default value. The child copies that stale value and, being a stored field, keeps it forever: nothing re-triggers its computation afterwards.

Example:
```python
parent = env['res.partner'].create({'name': 'Parent Co'})
child = env['res.partner'].create({'name': 'Child Address', 'parent_id': parent.id})
child.vat = 'BE0477472701'   # queues the child's compute first
parent.vat = 'BE0477472701'  # queues the parent's compute second
child.vies_valid   # False, even though the VAT is valid
parent.vies_valid  # True
```

**Desired behavior after PR is merged:**

Every partner without a parent is always computed before any child that may reuse its value, regardless of the batch's original order — so the child correctly ends up with the parent's real `vies_valid`.

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Forward-Port-Of: odoo/odoo#279927