[FLINK-39528][python] Update apache-arrow to 19.0.0

[mateczagany]

What is the purpose of the change

Update apache-arrow to 19.0.0 in flink-python

Brief change log

• Update apache-arrow to 19.0.0
• Remove Netty version pin since the new Arrow version uses Netty 4.2.x
• Update license

Verifying this change

This is a dependency upgrade, CI should pass

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

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

• Yes (please specify the tool below)

[flinkbot]

CI report:

• 19b35e8 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[spuru9]

LGTM if CI passes

[ferenc-csaky]

LGTM, but let's wait for @snuyanzin to make sure he also agrees