Tests: Coverage for verdi process commands when no connection can be established

[agoscinski]

From PR #6575 it became clear that a lot of unattended behavior can happen when the commands fail on the worker side

Process 1                           Process 2
Actioner (verdi command) ---RMQ--->  Worker (failure and gets stuck)

We need to test the commands better in cases the worker is when no connection can be established. Basically #6575 for the other verdi process commands (at least for play, pause).