Add Test/Example for `FairRunOnline`

[ChristianTackeGSI]

Is your feature request related to a problem? Please describe.
It looks like examples/advanced/MbsTutorial/ is the only part of the code that tests / is an example for FairRunOnline. As MBS was deprecated and scheduled for removal in FairRoot 19.2 or 20 (See #1084), this test/example will go away as well.

Describe the solution you'd like
There should be another test / example for FairRunOnline. Either from a real world scenario, or with some mock tooling behind it.

Describe alternatives you've considered
One could leave FairRunOnline untested. But this hinders refactoring a lot, because one feels unsure whether the changes actually work out.

Additional context
I am aware there is a difference between test and example. I am mostly concerned about test here, so that code refactoring can be done with much more confidence.

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