[FLINK-27748][Runtime/Coordination] AdaptiveScheduler support operator fixed parallelism

[jlon]

What is the purpose of the change

In the job topology, if the user specifies the concurrency of the operator, AdaptiveScheduler should support the operator's maximum parallelism equal to the user-specified parallelism during the scheduling process.
And the minimum parallelism is equal to the number of slots available to the cluster.
This is especially useful in certain scenarios,
For example, the parallelism of an operator that consumes Kafka is specified to be equal to the number of partitions. Or you want to control the write rate of the operator, etc.

Verifying this change

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? (yes)
• If yes, how is the feature documented? (docs)

[flinkbot]

CI report:

• dfcd0cc Azure: FAILURE

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[github-actions]

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[github-actions]

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