[ts3server] MariaDB prompt might do the opposite as it should

User reported:

```
Do you want to use MariaDB/MySQL instead of sqlite (Database Server including user and database already has to be set up!)? [y/N] N

checking if libmariadb2 is installed
=================================
libmariadb2 installed.

Configuring TeamSpeak 3 Server for MariaDB/MySQL
```

So this needs to be checked.