Description of problem:
When running foreman-maintain via automation, you usually do not want to see all the successful steps. Especially if the "automation" is the good old cron, that sends mail of all the output it gathers.

It is custom to have a cli flag (like --quiet or --batch or --cron) that suppresses all output unless there was an issue. In this case the failing step is printed (sometimes also the successful ones, I don't mind too much either way, whatever is easier to implement).

Version-Release number of selected component (if applicable):
6.12.0 and any other

How reproducible:
100%

Steps to Reproduce:
1. run `foreman-maintain backup online --assumeyes /var/tmp/backup` via cron

Actual results:
you get mail even if the run was successful

Expected results:
no output and thus no mail unless there was an error

Additional info: