refactor: do some internal refactor.

source/dnode/mnode/impl/src/mndSubscribe.c

@@ -357,10 +357,11 @@ static int32_t mndDoRebalance(SMnode *pMnode, const SMqRebInputObj *pInput, SMqR
   if (numOfFinal) {
     minVgCnt = totalVgNum / numOfFinal;
     imbConsumerNum = totalVgNum % numOfFinal;
-  }
-
     mInfo("sub:%s mq re-balance %d consumers: at least %d vgs each, %d consumers has 1 more vgroups than avg value",
           pSubKey, numOfFinal, minVgCnt, imbConsumerNum);
+  } else {
+    mInfo("sub:%s no consumer subscribe this topic", pSubKey);
+  }
 
   // 5. first scan: remove vgroups from te consumers, who have more vgroups than the threashold value that is
   // minVgCnt, and then put them into the recycled hash list