[FIX] sale_project: analytic default plan

issue: When creating a sale order, with a service that involves the creation of a project, with analytic accounting activated, the default analytic account is not the default one set in the settings of the Project app.

Steps to reproduce the issue :
- activate analytic accounting in the Accounting app.
- in the settings of the Project app, set the default analytic plan to any value but the first one.
- create a product in the Sale app, with a product type 'Service', that involves the creation of a 'Project'.
- create a sale order with the product
- go in the analytic accounting menu in Accounting app
 -> the analytic plan is not the one set by default in the settings of the Project app.

closes odoo/odoo#114302

Task: 3169483
X-original-commit: e801b3fa1bbc31713375cc669c6d47b32b175f53
Signed-off-by: Quentin De Paoli <qdp@odoo.com>
Signed-off-by: hupo-odoo <hupo@odoo.com>

addons/sale_project/models/sale_order.py

@@ -163,3 +163,8 @@ class SaleOrder(models.Model):
         if 'state' in values and values['state'] == 'cancel':
             self.project_id.sudo().sale_line_id = False
         return super(SaleOrder, self).write(values)
+
+    def _prepare_analytic_account_data(self, prefix=None):
+        result = super(SaleOrder, self)._prepare_analytic_account_data(prefix=prefix)
+        result['plan_id'] = self.company_id.analytic_plan_id.id or result['plan_id']
+        return result