[FLINK-32695] [Tests] Replace NonSerializableTupleSource with DataGeneratorSource V2 API

[Poorvankbhatia]

What is the purpose of the change

This pull request migrates NonSerializableTupleSource from the deprecated SourceFunction API to the new Source V2 API using DataGeneratorSource.

Brief change log

• Replaced NonSerializableTupleSource (SourceFunction) with DataGeneratorSource and GeneratorFunction
• Added explicit TypeInformation creation for Tuple2<Integer, NonSerializable>
• Removed obsolete NonSerializableTupleSource class

Verifying this change

This change is already covered by existing tests, such as StreamingOperatorsITCase#testAsyncWaitOperator which verifies that async operators handle both ordered and unordered processing of non-serializable
data types correctly.

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)

[Poorvankbhatia]

Hey @afedulov . Please have a look. Thanks :)

[flinkbot]

CI report:

• d23e78c Azure: SUCCESS

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