Removed unneeded override_system_checks

Refs #23685.

tests/fixtures_model_package/tests.py

@@ -5,7 +5,6 @@ import warnings
 from django.core import management
 from django.db import transaction
 from django.test import TestCase, TransactionTestCase
-from django.test.utils import override_system_checks
 from django.utils.six import StringIO
 
 from .models import Article, Book
@@ -31,7 +30,6 @@ class TestNoInitialDataLoading(TransactionTestCase):
 
     available_apps = ['fixtures_model_package']
 
-    @override_system_checks([])
     def test_migrate(self):
         with transaction.atomic():
             Book.objects.all().delete()
@@ -43,7 +41,6 @@ class TestNoInitialDataLoading(TransactionTestCase):
             )
             self.assertQuerysetEqual(Book.objects.all(), [])
 
-    @override_system_checks([])
     def test_flush(self):
         # Test presence of fixture (flush called by TransactionTestCase)
         self.assertQuerysetEqual(