[TD-3683]<fix>: reduce buffer size for more stable table creation. (#5719)

Co-authored-by: NShuduo Sang <sdsang@taosdata.com>

src/kit/taosdemo/taosdemo.c

@@ -2573,10 +2573,7 @@ static void* createTable(void *sarg)
   int64_t  lastPrintTime = taosGetTimestampMs();
 
   int buff_len;
-  if (superTblInfo)
-    buff_len = superTblInfo->maxSqlLen;
-  else
-    buff_len = BUFFER_SIZE;
+  buff_len = BUFFER_SIZE / 8;
 
   char *buffer = calloc(buff_len, 1);
   if (buffer == NULL) {
@@ -2624,7 +2621,7 @@ static void* createTable(void *sarg)
           return NULL;
         }
         len += snprintf(buffer + len,
-                superTblInfo->maxSqlLen - len,
+                buff_len - len,
                 "if not exists %s.%s%d using %s.%s tags %s ",
                 winfo->db_name, superTblInfo->childTblPrefix,
                 i, winfo->db_name,
@@ -2632,7 +2629,7 @@ static void* createTable(void *sarg)
         free(tagsValBuf);
         batchNum++;
         if ((batchNum < superTblInfo->batchCreateTableNum)
-                && ((superTblInfo->maxSqlLen - len)
+                && ((buff_len - len)
                     >= (superTblInfo->lenOfTagOfOneRow + 256))) {
           continue;
         }