nkurihar

Fixes #446 ### Motivation We found an ack failure issue: #446 MessageListeners can start to process messages before subscribing all child topics are completed in "multi topics" (e.g. partitioned, list,...

### Search before asking - [X] I searched in the [issues](https://github.com/apache/pulsar-client-cpp/issues) and found nothing similar. ### Version main branch commit id: 8b2753a56579ea6cf11e26a0c5a160797518df63 ### Minimal reproduce step 1. publish a certain...