Step to reproduce:
- Create leave type approved by the employee manager (and no limit
 allocation)
- Set User A with user B as his manager
- Set User C as a time off Officer
- As user A request leaves of the before-mentionned type
- As user C, try to approve A's leave request

Current behaviour:
- Leave is accepted
 Since V15, the groups have change and `is_officer` no longer
 represent time_off all approver but time_off officer.
 All approver are now timeoff Administrator and so the right
 of time off officer should be limited.

Behaviour after PR:
- Error is shown to the current user explaining that he need to
 be the current employee manager.

opw-2753845

closes odoo/odoo#86629

Signed-off-by: Kevin Baptiste <kba@odoo.com>