main_config.ipynb: Use database default port 8563

[ThomasBestfleisch]

Please set 8563 as the Port in Database Connection

For BucketFS it is common to use 2580 at least if you look around in the documentation (e.g. https://docs.exasol.com/db/latest/administration/on-premise/manage_network/system_network_settings.htm)
however it might be even better to leave the field empty instead of setting 6666

[tkilias]

We probably should also change the bucketfs port