Reader does not support finding partitions and create partitioned reader

#### Expected behavior

reader should recognize partitioned topic and work with them

#### Actual behavior

reader creates a non-partition topic even partitioned ones exist

#### Steps to reproduce

create reader on a partitioned-topic

#### System configuration
**Pulsar version**: 2.9.2

Reproduce the issue by creating a reader for a partitioned topic against Pulsar 2.9.2, then trace the Go client’s reader creation and partition-discovery path. Done means the reader recognizes an existing partitioned topic and creates a partitioned reader instead of a non-partition reader.

Written by the indexing model from the issue text.