[REM] api: remove helpers one and aggregate
[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) <fcee45b878db1f337818c5c606c1542797080a40@openerp.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo