[to #381] Add more integration tests for Kafka sink

[pingyu]

What problem does this PR solve?

Issue Number: ref #381

Problem Description: TBD

What is changed and how does it work?

• Add "sigstop" & "stop_downstream" integration test cases for Kafka sink
• Improve "kafka consumer" to properly handle errors on emitting event changes to downstream TiKV.
• Improve stability of downloading binaries
  • Failure case: https://do.pingcap.net/jenkins/blue/organizations/jenkins/tikv%2Fmigration%2Fpull_integration_kafka_test/detail/pull_integration_kafka_test/6/pipeline/52
  • Ref: https://github.com/pingcap/tiflow/blob/release-7.5/scripts/download-integration-test-binaries.sh
• Do not raise error on flow_control case for Kafka sink. Address possible memory leak later. Ref cdc,tests: integration test flow_control case is flaky #383.

Code changes

Check List for Tests

This PR has been tested by at least one of the following methods:

• Integration test

Side effects

• No side effects

Related changes

• No related changes

To reviewers

Please follow these principles to check this pull requests:

• Concentration. One pull request should only do one thing. No matter how small it is, the change does exactly one thing and gets it right. Don't mix other changes into it.
• Tests. A pull request should be test covered, whether the tests are unit tests, integration tests, or end-to-end tests. Tests should be sufficient, correct and don't slow down the CI pipeline largely.
• Functionality. The pull request should implement what the author intends to do and fit well in the existing code base, resolve a real problem for TiDB/TiKV users. To get the author's intention and the pull request design, you could follow the discussions in the corresponding GitHub issue or internal.tidb.io topic.
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• Performance. If you find the pull request may affect performance, you could ask the author to provide a benchmark result.

(The above text mainly refers to TiDB Development Guide. It's also highly recommended to read about Writing code review comments)

[pingyu]

/test ?

[ti-chi-bot]

@pingyu: The following commands are available to trigger required jobs:

• /test pull-integration-kafka-test
• /test pull-integration-test
• /test pull-unit-test

Use /test all to run all jobs.

In response to this:

/test ?

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[pingyu]

/test pull-integration-kafka-test
/test pull-unit-test

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/test pull-unit-test

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/retest

[pingyu]

/retest

[pingyu]

/retest

[pingyu]

/retest

[pingyu]

/retest

[pingyu]

/test ?

[ti-chi-bot]

@pingyu: The following commands are available to trigger required jobs:

• /test pull-integration-kafka-test
• /test pull-integration-test
• /test pull-unit-test

Use /test all to run all jobs.

In response to this:

/test ?

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[pingyu]

/test all

[pingyu]

/test pull-unit-test

[pingyu]

/test pull-integration-kafka-test
/test pull-integration-test

[pingyu]

/retest

[pingyu]

/retest

[pingyu]

/retest

[purelind]

/retest

[purelind]

/retest

[purelind]

/retest

[pingyu]

/test pull-integration-kafka-test

[pingyu]

/test pull-integration-kafka-test

[zeminzhou]

LGTM