[fix] Fix flaky test in negative_acks_tracker_test.go

[RobertIndie]

Fixes #1016

Motivation

The test for negative ack trackers needs to wait sometime to close the message channel. We use this interval time to assert that the negativeAckTracker can trigger the redelivering with the correct time interval. But we can't assert this interval very precisely due to the concurrent execution. Currently, we reserve only one millisecond for this concurrent execution:

pulsar-client-go/pulsar/negative_acks_tracker_test.go

Lines 45 to 49 in 3367cc0

	if nackBackoffPolicy == nil {
	time.Sleep(testNackDelay + 101*time.Millisecond)
	} else {
	time.Sleep(nackBackoffPolicy.Next(1) + 101*time.Millisecond)
	}

Here, 100 milliseconds is for the client tick delay. But we only wait for another 1 millisecond. This seems too short and introduces the flaky.

This PR waits for more 200 milliseconds. This will not affect the correctness of the test. Because the minimum interval NackDelay we used in these tests is 300 milliseconds. Waiting more 200 milliseconds will not affect the test result.

Modifications

• Wait for more 200 milliseconds to reduce the flaky

Does this pull request potentially affect one of the following parts:

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API: (yes / no)
• The schema: (yes / no / don't know)
• The default values of configurations: (yes / no)
• The wire protocol: (yes / no)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / GoDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation