Fix the 'essentials already started' bug

A service in the undefined state is dead, since it does not exist in the container list generated by the backend.
Add also a column indicating if a service is essential or not in the command line client, to aid debugging.
5 jobs for bugs/essentials-already-started in 2 minutes and 53 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Static Test
passed #3680
docs-test

00:00:43

passed #3678
pylint

00:00:49

passed #3679
unittests

00:00:46

 
  Integration Test
passed #3681
api-test

00:01:42

 
  Deploy
passed #3682
mirror-github

00:00:21