[FLINK-40214][table] Preserve JSON_OBJECTAGG key when wrapping value

[Au-Miner]

What is the purpose of the change

This PR fixes incorrect JSON_OBJECTAGG results when the key and value reference the same input field. Previously, object keys could contain additional escaped quotation marks.

Brief change log

• Update WrapJsonAggFunctionArgumentsRule#wrapJsonAggregate to replace only the value argument with its wrapped projection while preserving the original JSON_OBJECTAGG key argument.
• Update the optimized plan snapshots for regular, group-window, and window TVF aggregations.

Verifying this change

JsonAggregationFunctionsITCase adds regression coverage for regular and tumbling-window aggregations where the key and value use the same field.

The expected result is:

{"A":"A","B":"B"}

The WrapJsonAggFunctionArgumentsRuleTest plan snapshots verify that only the value argument references the JSON_STRING projection.

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

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

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

[flinkbot]

CI report:

• a0b615f Azure: SUCCESS

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[Au-Miner]

@xuyangzhong, could you please take a look?