[FLINK-32848][tests][JUnit5 migration] Migrate flink-runtime/shuffle tests to JUnit5

[X-czh]

What is the purpose of the change

Migrate flink-runtime/shuffle tests to JUnit5.

Verifying this change

The change itself is for migrating UT.

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

[flinkbot]

CI report:

• 303b120 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[ferenc-csaky]

Thanks for making these chamges, added 2 improvement suggestions.

[ferenc-csaky]

LGTM!

[X-czh]

Hi @1996fanrui, could you review the change when you are free, much appreciated~

[X-czh]

Hi @FangYongs, could you help check the change when you are free?

[FangYongs]

Thanks @X-czh for contributions, LGTM