[FIX] account_financial_report: Fix tests + sql for integration tests

When this module is installed along with other chart account different from generic one,
the number of expected accounts and the computation change (for example, in Spain,
the unaffected earnings account is 129000, choking with group with code prefix 1).

This commit makes the tests resistent to these changes.

account_financial_report/tests/abstract_test.py

@@ -12,7 +12,7 @@ _logger = logging.getLogger(__name__)
 
 class AbstractTest(common.TransactionCase):
     """Common technical tests for all reports."""
-    at_install = True
+    at_install = False
     post_install = True
 
     accounts = {}
@@ -289,9 +289,10 @@ class AbstractTest(common.TransactionCase):
             # Same filters with only one account
             current_filter = self.base_filters.copy()
             current_filter.update(filters)
+            report_accounts = report.account_ids.filtered('account_id')
             current_filter.update({
                 'filter_account_ids':
-                    [(6, 0, report.account_ids[0].account_id.ids)],
+                    [(6, 0, report_accounts[0].account_id.ids)],
             })
 
             report2 = self.model.create(current_filter)
@@ -299,7 +300,7 @@ class AbstractTest(common.TransactionCase):
 
             self.assertEqual(len(report2.account_ids), 1)
             self.assertEqual(report2.account_ids.name,
-                             report.account_ids[0].name)
+                             report_accounts[0].name)
 
             if self._partner_test_is_possible(filters):
                 # Same filters with only one partner