refact getPublishTopicList method and subscriptions method redundant code

[xichaodong]

There are two redundancy statement code

1. getPublishTopicList()：can replace with hashmap constructor
2. subscriptions(): can replace with hashmap constructor

[duhenglucky]

Just go ahead~

[github-actions]

This issue is stale because it has been open for 365 days with no activity. It will be closed in 3 days if no further activity occurs.

[github-actions]

This issue was closed because it has been inactive for 3 days since being marked as stale.