fix td-1706: leak of connection id

src/rpc/src/rpcMain.c

@@ -1051,6 +1051,9 @@ static void *rpcProcessMsgFromPeer(SRecvInfo *pRecv) {
     if (code != 0) { // parsing error
       if (rpcIsReq(pHead->msgType)) {
         rpcSendErrorMsgToPeer(pRecv, code);
+        if (code == TSDB_CODE_RPC_INVALID_TIME_STAMP || code == TSDB_CODE_RPC_AUTH_FAILURE) {
+          rpcCloseConn(pConn);
+        }
         tDebug("%s %p %p, %s is sent with error code:0x%x", pRpc->label, pConn, (void *)pHead->ahandle, taosMsg[pHead->msgType+1], code);
       } 
     } else { // msg is passed to app only parsing is ok