Original PR description

Issue:
- The `_load_pos_data` method was fetching all `account.move` records instead of only those related to the POS orders of the selected configuration.
- This caused MemoryError

Cause:
- The [_load_pos_data](https://github.com/odoo/enterprise/blob/saas-18.3/pos_settle_due/models/account_move.py#L18-L20) method used an empty domain (`[]`) because the `_load_pos_data_domain` method was not properly implemented.
- As a result, `search_read` fetched all available `account.move` records in the system, regardless of the POS config context.

Fix:
- This commit implements `_load_pos_data_domain` to:
  - Retrieve only POS orders for the current config with linked invoices.
  - Extract their related `account.move` IDs.
  - Return a domain to limit the search to only those move IDs.
 
```
rari_3017353=> select count(*) from account_move;
  count  
---------
 1607249
(1 row)
```
task-4920625