Avoid get partition metadata while the topic name is a partition name. (

#6339)

Motivation

To avoid get partition metadata while the topic name is a partition name.
Currently, if users want to skip all messages for a partitioned topic or unload a partitioned topic, the broker will call get topic metadata many times. For a topic with the partition name, it is not necessary to call get partitioned topic metadata again.

(cherry picked from commit 26d569b)