[FLINK-35468] Update isEnableAutoAcknowledgeMessage config comment

[geniusjoe]

Purpose of the change

Since we deleted shared and key-shared subscription type in pulsar source connector, I think it is better to remove these subscription type in isEnableAutoAcknowledgeMessage option comment to prevent misunderstanding.

Brief change log

update SourceConfiguration.java isEnableAutoAcknowledgeMessage comment.

Significant changes

• Dependencies have been added or upgraded
• Public API has been changed (Public API is any class annotated with @Public(Evolving))
• Serializers have been changed
• New feature has been introduced

[boring-cyborg]

Thanks for opening this pull request! Please check out our contributing guidelines. (https://flink.apache.org/contributing/how-to-contribute.html)

[syhily]

Shared subscription won't be introduced to Connector anymore. We will only use the Exclusive subscription because the Flink can handle the fallover logic internally. So the comments can be simplified.

[geniusjoe]

Shared subscription won't be introduced to Connector anymore. We will only use the Exclusive subscription because the Flink can handle the fallover logic internally. So the comments can be simplified.

Thanks for your reply. Would you mind merge this pr?

[boring-cyborg]

Awesome work, congrats on your first merged pull request!