cdc,tests: `kafkaSuite.TestNewSaramaProducer` is flaky

[pingyu]

Bug Report

1. Describe the bug

2. Minimal reproduce step (Required)

Run unit tests in CI.

3. What did you see instead (Required)

=== Failed
=== FAIL: cdc/sink/producer/kafka Test (60.55s)

----------------------------------------------------------------------
FAIL: kafka_test.go:65: kafkaSuite.TestNewSaramaProducer

kafka_test.go:167:
    c.Assert(err, check.IsNil)
... value *errors.withStack = [CDC:ErrKafkaSendMessage]kafka send message failed: kafka: Failed to deliver 2 messages. ("[CDC:ErrKafkaSendMessage]kafka send message failed: kafka: Failed to deliver 2 messages.")

[2024/01/20 23:17:19.226 +08:00] [ERROR] [kafka.go:222] ["close async client with error"] [error="kafka: Failed to deliver 1 messages."] [stack="github.com/tikv/migration/cdc/cdc/sink/producer/kafka.(*kafkaSaramaProducer).Close\n\t/home/jenkins/agent/workspace/tikv/migration/pull_unit_test/migration/cdc/cdc/sink/producer/kafka/kafka.go:222\ngithub.com/tikv/migration/cdc/cdc/sink/producer/kafka.(*kafkaSuite).TestProducerSendMessageFailed.func4\n\t/home/jenkins/agent/workspace/tikv/migration/pull_unit_test/migration/cdc/cdc/sink/producer/kafka/kafka_test.go:364\ngithub.com/tikv/migration/cdc/cdc/sink/producer/kafka.(*kafkaSuite).TestProducerSendMessageFailed\n\t/home/jenkins/agent/workspace/tikv/migration/pull_unit_test/migration/cdc/cdc/sink/producer/kafka/kafka_test.go:397\nreflect.Value.call\n\t/usr/local/go/src/reflect/value.go:596\nreflect.Value.Call\n\t/usr/local/go/src/reflect/value.go:380\ngithub.com/pingcap/check.(*suiteRunner).forkTest.func1\n\t/go/pkg/mod/github.com/pingcap/check@v0.0.0-20211026125417-57bd13f7b5f0/check.go:850\ngithub.com/pingcap/check.(*suiteRunner).forkCall.func1\n\t/go/pkg/mod/github.com/pingcap/check@v0.0.0-20211026125417-57bd13f7b5f0/check.go:739"]

OOPS: 8 passed, 1 FAILED

DONE 231 tests, 1 failure in 545.334s

make: *** [unit_test_in_verify_ci] Error 1

4. What did you expect to see? (Required)

Test succeed.

5. What is your migration tool and TiKV version? (Required)

• TiKV:
• TiKV CDC: #387 900ebfdceb65dff43e69663632e33234a4cd664c
• TiKV BR:
• TiKV Online Bulk Load:

[pingyu]

Close by #392