Remove flaky batch notifier unit test

The test_queue_event_multiple_events_notify_method()
can be flaky depending on the performance of the SUT,
where sometimes the notifier is called thrice instead
of the expected twice, making in unreliable. As we are
already testing all the notification events arrived in
test_queue_event_multiple_events_callback_method(),
let's remove the other test.

Closes-bug: #2100806
Change-Id: I193b4cba5b31ff9baa90992a11db70e5b65ec569

neutron/tests/unit/notifiers/test_batch_notifier.py

@@ -26,7 +26,7 @@ class TestBatchNotifier(base.BaseTestCase):
     def setUp(self):
         super().setUp()
         self._received_events = queue.Queue()
-        self.notifier = batch_notifier.BatchNotifier(0.2, self._queue_events)
+        self.notifier = batch_notifier.BatchNotifier(0.1, self._queue_events)
         self.spawn_n_p = mock.patch.object(utils, 'spawn_n')
 
     def _queue_events(self, events):
@@ -45,26 +45,6 @@ class TestBatchNotifier(base.BaseTestCase):
         self.assertEqual(1, len(self.notifier._pending_events.queue))
         self.assertEqual(1, spawn_n.call_count)
 
-    def test_queue_event_multiple_events_notify_method(self):
-        def _batch_notifier_dequeue():
-            while not self.notifier._pending_events.empty():
-                self.notifier._pending_events.get()
-
-        c_mock = mock.patch.object(self.notifier, '_notify',
-                                   side_effect=_batch_notifier_dequeue).start()
-        events = 20
-        for i in range(events):
-            self.notifier.queue_event('Event %s' % i)
-            time.sleep(0)  # yield to let coro execute
-
-        utils.wait_until_true(self.notifier._pending_events.empty,
-                              timeout=5)
-        # Called twice: when the first thread calls "synced_send" and then,
-        # in the same loop, when self._pending_events is not empty(). All
-        # self.notifier.queue_event calls are done in just one
-        # "batch_interval" (2 secs).
-        self.assertEqual(2, c_mock.call_count)
-
     def test_queue_event_multiple_events_callback_method(self):
         events = 20
         for i in range(events):