[REM] api: remove helpers one and aggregate

`api.one` has been deprecated since v9 because it often makes the code
less clear and behaves in ways developers and readers may not expect
since functions decorated with it usually expect a `list` of record(s)
instead of the recordset, whereas most modern Odoo code expects `self`
to be a recordset.

The function `aggregate` was solely being used by `api.one` thus it has
also been removed since there doesn't seem to be any other use for it
thus far.

closes odoo/odoo#34555

Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

odoo/api.py

@@ -34,7 +34,7 @@
 __all__ = [
     'Environment',
     'Meta', 'guess', 'noguess',
-    'model', 'multi', 'one',
+    'model', 'multi',
     'model_cr', 'model_cr_context',
     'cr', 'cr_context',
     'cr_uid', 'cr_uid_context',
@@ -275,19 +275,6 @@ def downgrade(method, value, self, args, kwargs):
         return value.ids
 
 
-def aggregate(method, value, self):
-    """ Aggregate record-style ``value`` for a method decorated with ``@one``. """
-    spec = getattr(method, '_returns', None)
-    if spec:
-        # value is a list of instances, concatenate them
-        model, _, _ = spec
-        if model == 'self':
-            return sum(value, self.browse())
-        elif model:
-            return sum(value, self.env[model])
-    return value
-
-
 def split_context(method, args, kwargs):
     """ Extract the context from a pair of positional and keyword arguments.
         Return a triple ``context, args, kwargs``.
@@ -337,42 +324,6 @@ def multi(method):
     return method
 
 
-def one(method):
-    """ Decorate a record-style method where ``self`` is expected to be a
-        singleton instance. The decorated method automatically loops on records,
-        and makes a list with the results. In case the method is decorated with
-        :func:`returns`, it concatenates the resulting instances. Such a
-        method::
-
-            @api.one
-            def method(self, args):
-                return self.name
-
-        may be called in both record and traditional styles, like::
-
-            # recs = model.browse(cr, uid, ids, context)
-            names = recs.method(args)
-
-            names = model.method(cr, uid, ids, args, context=context)
-
-        .. deprecated:: 9.0
-
-            :func:`~.one` often makes the code less clear and behaves in ways
-            developers and readers may not expect.
-
-            It is strongly recommended to use :func:`~.multi` and either
-            iterate on the ``self`` recordset or ensure that the recordset
-            is a single record with :meth:`~odoo.models.Model.ensure_one`.
-    """
-    def loop(method, self, *args, **kwargs):
-        result = [method(rec, *args, **kwargs) for rec in self]
-        return aggregate(method, result, self)
-
-    wrapper = decorator(loop, method)
-    wrapper._api = 'one'
-    return wrapper
-
-
 def model_cr(method):
     """ Decorate a record-style method where ``self`` is a recordset, but its
         contents is not relevant, only the model is. Such a method::