Leadership movement proposal should not generated when client just want to change topic replication factor.

[kidkun]

In current code, if client sends a request to topic_configuration endpoint to increase/decrease some topics' replication factor, the generated proposals may have leadership movements of irrelevant topics. Through in most case these leadership movements are very fast to execute, it is counter-intuitive to user that there are movements of irrelevant topics.
It is better to just generate minimal proposals to just fulfill the original request.