Groups with more than 3 digits exist, but none of the accounts are "hanging" from them. For example, the group of accounts 1030 and 1034 is 103, even though 1030 and 1034 groups exist. The account structure should concur with the account group structure. closes odoo/odoo#28420 Signed-off-by: Josse Colpaert <jco-odoo@users.noreply.github.com>