MDEV-21308 : WSREP: binlog ... cache not empty warnings on server with WSREP disabled

Remove output if wsrep is not enabled.

sql/log.cc

@@ -1650,7 +1650,7 @@ static int binlog_close_connection(handlerton *hton, THD *thd)
   binlog_cache_mngr *const cache_mngr=
     (binlog_cache_mngr*) thd_get_ha_data(thd, binlog_hton);
 #ifdef WITH_WSREP
-  if (cache_mngr && !cache_mngr->trx_cache.empty()) {
+  if (WSREP(thd) && cache_mngr && !cache_mngr->trx_cache.empty()) {
     IO_CACHE* cache= get_trans_log(thd);
     uchar *buf;
     size_t len=0;