[FLINK-39148] [Build] Update flink-connector-kafka & flink-sql-connector-kafka to 4.0.1-2.0

[eschcam]

What is the purpose of the change

flink-connector-kafka 3.0.0-1.17 contains the following CVEs:

• CVE-2025-27819
• CVE-2025-27818
• CVE-2025-27817
• CVE-2024-56128
• CVE-2024-31141
• CVE-2023-44981

Upgrading to 4.0.1-2.0 resolves all above CVEs

Brief change log

• Update flink-connector-kafka to 4.0.1-2.0
• Update flink-sql-connector-kafka to 4.0.1-2.0
• Use a variable for flink-connector-kafka version

Verifying this change

Passes CI tests

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

• Dependencies (does it add or upgrade a dependency): yes
• 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:

• 3fb5125 Azure: SUCCESS

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