[FIX] stock: fix check of package all in move lines

The `groupby` function is used to builds groups of(product, lot) keys
and their corresponding move lines / quants. `groupby` groups
*consecutive* keys, which is why the input is sorted by the keys.

`sorted` on recordsets keys will not sort as we would expect in this
particular situation, as the comparison operators on records act as
Set Comparison operators on the record ids, i.e. to compare the sets
superset/subset relationships:

```
>>> env["product.product"].browse(1) < env["product.product"].browse(2)
False
>>> env["product.product"].browse(1) < env["product.product"].browse([1, 2])
True
```

Example of sorted on stock.move.line records, where the product id 7313
is both in the slots 4 and 12 instead of being consecutive:

```
>>> [l.product_id.id for l in sorted(lines, key=itemgetter('product_id'))]
[7436, 7437, 7352, 7423, 7313, 7351, 7423, 7424, 7320, 7398, 7312, 7352, 7313, 7436, 7437, 7442, 7443, 7320, 7423, 7424, 7318, 7396, 7368, 7355, 7316]
```

Now when we group by id the 2 ids 7313 are correctly placed together in
slots 1 and 2:

```
>>> [l.product_id.id for l in sorted(lines, key=attrgetter('product_id.id'))]
[7312, 7313, 7313, 7316, 7318, 7320, 7320, 7351, 7352, 7352, 7355, 7368, 7396, 7398, 7423, 7423, 7423, 7424, 7424, 7436, 7436, 7437, 7437, 7442, 7443]
```

This commit aims to sort by "id" of the related records, to ensure the
same (product, lot) couples are consecutive.

closes odoo/odoo#71126

X-original-commit: 3317249d
Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>