[FLINK-24283][connector/pulsar] Use stick key consumer in Key_Shared subscription.

[syhily]

What is the purpose of the change

Use stick key consumer in Key_Shared subscription. This would make sure Pulsar won't treat the Flink reader as a shared consumer.

This fix apache/pulsar#12035

Brief change log

• Change consumer type in PulsarSourceEnumerator

Verifying this change

This change is already covered by existing tests, such as PulsarSourceKeySharedE2ECase in another PR.

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)

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Last check on commit 9a64e19 (Tue Sep 14 15:17:06 UTC 2021)

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[dawidwys]

Yes, I will in a bit

[dawidwys]

LGTM