[FLINK-40415][python] Fix Python 3.9 dependency conflict of grpcio-tools

[dianfu]

What is the purpose of the change

This pull request fixes the dependency conflicts after bumping the Apache Beam version

Brief change log

• Only install grpcio-tools on Python 3.10+
• Skip proto generation verification on Python 3.9

Verifying this change

This change is already covered by existing tests

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)

Generated-by: [Codex GPT-5.6 Sol]

[flinkbot]

CI report:

• 99201cb Azure: SUCCESS

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