[FLINK-39672][docs] Document Java records as supported POJO types

[liuml07]

What is the purpose of the change

This backports PR #28149 to release-2.2 for FLINK-39672

Java records have been supported as POJO types since Flink 1.19 (FLINK-32380), but the only doc mention lived on the release-1.20 java_compatibility page and was inadvertently removed on master by FLINK-37339.

Brief change log

• Restores the FLINK-32380 reference under "Java 17" in java_compatibility.md and notes that records are handled as POJO types serialized via their canonical constructor.
• Adds a note in both POJO listings in types_serialization.md that a public record class is serialized by PojoSerializer; the no-argument constructor and getter/setter requirements do not apply.
• Mentions in schema_evolution.md that records follow the same POJO schema evolution rules.

Parallel updates in docs/content.zh.

Verifying this change

Doc-only change.

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)

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Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: Claude Opus 4.7

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CI report:

• 26ec162 Azure: SUCCESS

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[snuyanzin]

@liuml07 instead of having AI as a co-author can you changed it to generated by as mentioned at
https://github.com/apache/flink/blame/1e6a73616eb4e224a149e684c832f20bcba93148/AGENTS.md#L327