[fix][test] Fix PersistentDispatcherFailoverConsumerTest#testAddRemoveConsumer wrong logic.

[mattisonchao]

Motivation

From issue #14540, I found this test has some logic problems.

Look at step 7 in the test. If we remove the last consumer, the active consumer will change. The logic you can see at AbstractDispatcherSingleActiveConsumer#pickAndScheduleActiveConsumer method.

At this time, We will get three notifications. The current new active consumer is consumer1, So If we remove consumer0. We will not get a notification.

I'm unsure if we can fix the #14540, but the original flaky relative logic is changed.

Modifications

• Fix the wrong test logic to fit the pickAndScheduleActiveConsumer.

Verifying this change

• Make sure that the change passes the CI checks.

Documentation

• doc-not-needed
  (Please explain why)

[lhotari]

LGTM