[FIX] account_financial_report: Refactor tests

Use core account test base, helping to ensure we have the correct accounting environment setup.
If any of the localization modules are loaded, this will make this tests be skipped, instead of simply failing

TT28423

account_financial_report/tests/test_open_items.py

@@ -2,12 +2,15 @@
 # Copyright 2016 Camptocamp SA
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
-from odoo.tests.common import TransactionCase
+from odoo.addons.account.tests.common import AccountTestInvoicingCommon
 
 
-class TestOpenItems(TransactionCase):
+class TestOpenItems(AccountTestInvoicingCommon):
+    @classmethod
+    def setUpClass(cls, chart_template_ref=None):
+        super().setUpClass(chart_template_ref=chart_template_ref)
+
     def test_partner_filter(self):
-        self.env.user.company_id = self.env.ref("base.main_company").id
         partner_1 = self.env.ref("base.res_partner_1")
         partner_2 = self.env.ref("base.res_partner_2")
         partner_3 = self.env.ref("base.res_partner_3")