[FLINK-36161][docs]Update Integration Test Example with Sink API.

[RanJinh]

What is the purpose of the change

To update the Testing Flink Jobs Docs example from deprecated SinkFunction to Sink.

Brief change log

• Using Sink instead of SinkFunction, since SinkFunction is deprecated in flink 1.20.

Verifying this change

• Document address:
  • https://nightlies.apache.org/flink/flink-docs-master/docs/dev/datastream/testing/#testing-flink-jobs
  • https://nightlies.apache.org/flink/flink-docs-master/zh/docs/dev/datastream/testing/#%e6%b5%8b%e8%af%95-flink-%e4%bd%9c%e4%b8%9a

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• 4524912 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[davidradl]

This is difficult to review without trying it. It would be great if this class or a variant was in Flink as a test class, with a comment to say if the class is changed then change the docs. In this way we should have a working test and valid docs.

[davidradl]

Reviewed by Chi on 12/12/24. Asked submitter questions

[RanJinh]

@flinkbot run azure