[fix] Fix DLQ producer name conflicts when multiples consumers send messages to DLQ

[crossoverJie]

Motivation

To keep consistent with the Java client.

Releted PR: apache/pulsar#21890

Explain here the context, and why you're making that change. What is the problem you're trying to solve.

Modifications

Set DLQ producerName fmt.Sprintf("%s-%s-%s-DLQ", r.topicName, r.subscriptionName, r.consumerName)

Verifying this change

• Make sure that the change passes the CI checks.

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

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): (no)
• The public API: (no)
• The schema: (no)
• The default values of configurations: (no)
• The wire protocol: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicable / docs / GoDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation

[crossoverJie]

@RobertIndie PTAL

[zzzming]

we just found this issue. Thanks for fixing it.