[improve][client] Enhance error handling for non-exist subscription in consumer creation

[Shawyeok]

Motivation

When allowAutoSubscriptionCreation is set to false on broker, creating a consumer for a subscription that does not exist does not throw a SubscriptionNotFoundException. Instead, it throws a PulsarClientException. This behavior complicates determining whether the subscription exists, requiring users to perform checks like getRootCause(e).getMessage().matches(".*Subscription .*does not exist.*") before #22164. Even after #22164, while the root cause becomes SubscriptionNotFoundException, additional handling is still necessary.

try {
    Consumer<byte[]> consumer = pulsarClient.newConsumer()
            .topic("public/default/subscription-auto-creation-disabled")
            .subscriptionName("test")
            .subscriptionType(SubscriptionType.Exclusive)
            .subscribe();
} catch (PulsarClientException.SubscriptionNotFoundException e) {
    // never reached here
} catch (PulsarClientException e) {
    getRootCause(e).getMessage().matches(".*Subscription .*does not exist.*");   // before #22164
    getRootCause(e) instanceof PulsarClientException.SubscriptionNotFoundException; // after #22164, there is another approach
}

Modifications

This change modifies the code to throw SubscriptionNotFoundException directly when attempting to create a consumer for a non-existent subscription. This exception is a subclass of PulsarClientException, ensuring backward compatibility and providing a clearer error handling path for users.

Verifying this change

• Ensure that the change passes the CI checks.

This PR also updates the corresponding test in org.apache.pulsar.client.api.MultiTopicsConsumerTest#testSubscriptionNotFound.

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

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: Shawyeok#17

[lhotari]

LGTM