fix(hc): Remove final stable=False (#60671)

This slipped in in-between
https://github.com/getsentry/sentry/pull/60498 being merged.

tests/sentry/api/endpoints/test_user_notification_email.py

@@ -16,7 +16,7 @@ class UserNotificationEmailTestBase(APITestCase):
         self.login_as(user=self.user)
 
 
-@control_silo_test(stable=True)
+@control_silo_test()
 class UserNotificationEmailGetTest(UserNotificationEmailTestBase):
     def test_populates_useroptions_for_email(self):
         UserEmail.objects.create(user=self.user, email="alias@example.com", is_verified=True).save()