[Bug] Failed to connect to Doris using Navicat version 15

**Describe the bug**
When navicat try to connect Doris, it will send statement:

```
SHOW VARIABLES LIKE 'lower_case_%'; SHOW VARIABLES LIKE 'sql_mode'; SELECT COUNT(*) AS support_ndb FROM information_schema.ENGINES WHERE Engine = 'ndbcluster';
```

And Doris will return "Syntax error".

**WHy**
This is because the MySQL protocol layer of Doris does not support multi-statement.
