[FIX] sale_timesheet: missing onchange

The onchange is defined on the projduct.template, but the user
can edit the product configuration from a SO: it will be the
form view of product.product.
This commit applies the onchange of the product template
on the product product.

closes odoo/odoo#29140

addons/sale_timesheet/models/product.py

@@ -85,3 +85,17 @@ class ProductTemplate(models.Model):
             self.service_type = 'timesheet'
         elif self.type == 'consu' and self.service_policy == 'ordered_timesheet':
             self.invoice_policy = 'order'
+
+
+class ProductProduct(models.Model):
+    _inherit = 'product.product'
+
+    @api.onchange('service_tracking')
+    def _onchange_service_tracking(self):
+        if self.service_tracking == 'no':
+            self.project_id = False
+            self.project_template_id = False
+        elif self.service_tracking == 'task_global_project':
+            self.project_template_id = False
+        elif self.service_tracking in ['task_new_project', 'project_only']:
+            self.project_id = False