[FLINK-15550][runtime] The static latches in TaskTest were replaced by latches from invokable objects

[akalash]

What is the purpose of the change

Backport for #21763

Brief change log

The static latches in TaskTest were replaced by latches from invokable objects in order to avoid accidental sharing latches between multiple tests

Verifying this change

It's test

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• dfeb9e2 Azure: SUCCESS

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[akalash]

@pnowojski, Can you take a look at it please? it is just a backport of the ticket which you have reviewed already. There was no any conflicts