During `retrying` method we still don't have any uid on the
current env (the authentification is inside the `func` ->
`_serve_ir_http`). If there is an Integrity Error coming from the
method/controller called, the error is catch by `retrying` and call
`_sql_error_to_message` leading to a traceback:

```
...
File "/home/odoo/src/odoo/saas-18.2/odoo/http.py", line 2016, in _transactioning
  return service_model.retrying(func, env=self.env)
File "/home/odoo/src/odoo/saas-18.2/odoo/service/model.py", line 186, in retrying
  message = env._("The operation cannot be completed: %s", model._sql_error_to_message(exc))
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 2916, in _sql_error_to_message
  cons_rec = self.env['ir.model.constraint'].search_fetch([
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 1390, in search_fetch
  query = self._search(domain, offset=offset, limit=limit, order=order or self._order)
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 4993, in _search
  self.browse().check_access('read')
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 3719, in check_access
  if not self.env.su and (result := self._check_access(operation)):
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 3752, in _check_access
  if not Access.check(self._name, operation, raise_exception=False):
File "/home/odoo/src/odoo/saas-18.2/odoo/addons/base/models/ir_model.py", line 2051, in check
  has_access = model in self._get_allowed_models(mode)
File "decorator.py", line 232, in fun
  return caller(func, *(extras + args), **kw)
File "/home/odoo/src/odoo/saas-18.2/odoo/tools/cache.py", line 125, in lookup
  value = d[key] = self.method(*args, **kwargs)
File "/home/odoo/src/odoo/saas-18.2/odoo/addons/base/models/ir_model.py", line 2023, in _get_allowed_models
  group_ids = self.env.user._get_group_ids()
File "decorator.py", line 232, in fun
  return caller(func, *(extras + args), **kw)
File "/home/odoo/src/odoo/saas-18.2/odoo/tools/cache.py", line 125, in lookup
  value = d[key] = self.method(*args, **kwargs)
File "/home/odoo/src/odoo/saas-18.2/odoo/addons/base/models/res_users.py", line 1026, in _get_group_ids
  self.ensure_one()
File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 5497, in ensure_one
  raise ValueError("Expected singleton: %s" % self)
```
It actually hides the legit constraint message error.

Fix it by adding a sudo() to the constraint search, since whatever the
user (public or not), the error message should be accessible and
returned.

Currently a `ParseError` arises when we try to load the store data after deleting the `Food` Category in Invoicing.

Steps to reproduce:
---
- Install `Invoicing` application (without demo data).
- Invoicing > Configuration > Categories > Delete `Food`
- Now in POS try to load `Restaurant` and `Bar`

Traceback:
---
```
ValueError: External ID not found in the system: point_of_sale.product_category_food

ParseError: while parsing /home/odoo/src/odoo/saas-18.1/addons/pos_restaurant/data/scenarios/restaurant_data.xml:56, somewhere inside <record model="product.product" id="pos_food_bacon">
            <field name="name">Bacon Burger</field>
            <field name="list_price">15.50</field>
            <field name="standard_price">13.95</field>
            <field name="description_sale">200G Irish Black Angus beef, caramelized onions with paprika, chopped iceberg salad, red onions, grilled bacon, tomato sauce, pickles, barbecue sauce</field>
            <field name="type">consu</field>
            <field name="weight">0.01</field>
            <field name="uom_id" ref="uom.product_uom_unit"/>
            <field name="image_1920" type="base64" file="pos_restaurant/static/img/th-burger.png"/>
            <field name="available_in_pos" eval="True"/>
            <field name="categ_id" ref="point_of_sale.product_category_food"/>
            <field name="pos_categ_ids" eval="[(6, 0, [ref('food')])]"/>
        </record>
```

The error occurs because the user deleted the category, and then tried to load the store data, that references the missing product category.

This commit resolves the error by providing a False value for the field if the product category is missing.

sentry-6314696040

---
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