[FIX] l10n_pe: adapt account group

The account.group model has been refactored in
https://github.com/odoo/odoo/commit/a124050511d508f6f1f8a4d4f9dfb2fa1507ad98



Although the filename was correct (.template) and one field was changed
(code_prefix -> code_prefix_start), we don't accept a parent anymore and
we have to provide the chart of account id.

closes odoo/odoo#42302

X-original-commit: 079ebab64e1ea7c17d786c8b4d17bbb707ff856a
Signed-off-by: Josse Colpaert <jco@openerp.com>