[FLINK-15816][k8s] Limit kubernetes.cluster-id to a maximum of 40 characters

[alpreu]

What is the purpose of the change

Kubernetes labels have a maximum length of 63 characters. The longest created label is {cluster-id}-resourcemanager-leader, therefore the cluster-id has to be limited to 40 characters to not create failures on deployment.

Brief change log

• Updated MAXIMUM_CHARACTERS_OF_CLUSTER_ID to 40
• Updated docs

Verifying this change

This change is already covered by existing tests, such as (please describe tests).

• AbstractKubernetesParametersTest#testClusterIdLengthLimitation

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: (yes - kubernetes)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (docs + JavaDocs)

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Automated Checks

Last check on commit bc825a5 (Thu Nov 18 10:55:12 UTC 2021)

Warnings:

• No documentation files were touched! Remember to keep the Flink docs up to date!

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• ❓ 1. The [description] looks good.
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• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

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CI report:

• bc825a5 Azure: SUCCESS

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