[Bug] DLQ explicit set of topic name create it in public(tenant)/default(namespace)

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Version

2.11.0

### Minimal reproduce step

Ensure explicit set of name in deadLetterTopic
When it is not set DLQ created correctly in same tenant and namespace where original topic exists
When set such name directly it created as
persistent://public/default/test-topic-name-test-subscription-DLQ

.enableRetry(true)
.deadLetterPolicy(
DeadLetterPolicy
.builder()
.maxRedeliverCount(opts.maxRedeliverTimes)
.deadLetterTopic("test-topic-name-test-subscription-DLQ") // TODO
.initialSubscriptionName(sub.name.value)
.build()
)

### What did you expect to see?

DLQ topic should be in same tenant as namespace as original topic

### What did you see instead?

DLQ topic created as
persistent://public/default/test-topic-name-test-subscription-DLQ

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start from the DeadLetterPolicy builder and the explicit deadLetterTopic("test-topic-name-test-subscription-DLQ") call shown in the reproduction. Trace how that topic name is resolved when retry and dead-letter handling create the topic. Done means an explicitly named DLQ is created in the same tenant and namespace as the original topic, with regression coverage for the shown case.

Written by the indexing model from the issue text.