[hotfix][flink-tests] Fix duplicated dependency & plugin

[Dennis-Mircea]

What is the purpose of the change

Fix duplicated dependency & plugin in flink-tests module.

Brief change log

Updated the pom.xml.

Verifying this change

This change can be verified through the automatic PR CI workflow status.

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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[flinkbot]

CI report:

• b749933 Azure: SUCCESS

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