TypeError error for insecure calls to sqlalchemy db api

Call to `db.v2.sqlalchemy.api._get_collection` function with `insecure=True` and `fields` specified cause a call to `b.model_query(model, *columns)` with erroneous parameters.

```
Traceback (most recent call last):
  File "mistral/tests/unit/db/v2/test_sqlalchemy_db_api.py", line 3071, in test_get_event_triggers_specific_fields_insecure
    insecure=True)
  File "mistral/db/sqlalchemy/base.py", line 117, in _within_session
    result = func(*args, **kw)
  File "mistral/db/v2/sqlalchemy/api.py", line 1495, in get_event_triggers
    return _get_collection(model=models.EventTrigger, **kwargs)
  File "mistral/db/v2/sqlalchemy/api.py", line 262, in _get_collection
    query = (b.model_query(model, *columns) if insecure
  File "mistral/db/sqlalchemy/base.py", line 117, in _within_session
    result = func(*args, **kw)
TypeError: model_query() got multiple values for keyword argument 'session'
```