[FIX] website_hr_recruitment: fix broken display_name

With https://github.com/odoo/odoo/pull/122085,
we simplified the definition of display_name for `ir.department`:
https://github.com/odoo/odoo/commit/3c62ca1eb96d571b2b686b5caee370324c589ab4#diff-404a1cabe61e6fcb32cc3ac3d3d36336b9313f162130c3edbe1066c130b09c0dR11
but because of https://github.com/odoo/odoo/blob/0d30cc2bc9b9cc2b805d6c2d0a440f185c648da0/odoo/models.py#L235,
it overstates completely the default definition instead of
merging definition as others fields.

Fix the change.

closes odoo/odoo#131445

X-original-commit: 17eed41b81049a25db42a3e8389bd931433b0717
Related: odoo/enterprise#45579
Signed-off-by: Julien Castiaux (juc) <juc@odoo.com>
Signed-off-by: Rémy Voet (ryv) <ryv@odoo.com>

addons/website_hr_recruitment/models/hr_department.py

@@ -8,4 +8,4 @@ class Department(models.Model):
     _inherit = 'hr.department'
 
     # Get department name using superuser, because model is not accessible for portal users
-    display_name = fields.Char(compute_sudo=True)
+    display_name = fields.Char(compute='_compute_display_name', compute_sudo=True)