[6.16.z] Provide better error output for test_satellite_installation

[Satellite-QE]

Cherrypick of PR: #17105

Problem Statement

The current output of test_satellite_installation is useless. Because the output is so long, pytest truncates it which hides the relevant error.

Solution

As a first step, it does a trivial cleanup for readability. The next commit stops using len(x) == 0 and instead uses not x to assert there is no output. I haven't tested this, but I believe this allows pytest to skip a layer of output and hopefully also provide better output.

The real change is that it asserts the exit code of the installer to be 0 or 2. In practice I'd always expect 2, but 0 is also valid. See https://github.com/theforeman/kafo?tab=readme-ov-file#exit-code for more information. Since foreman-installer 3.8.0 (theforeman/foreman-installer@0d2fb67) it also displays structured output on the exact failure.

Related Issues

trigger: test-robottelo
pytest: tests/foreman/ui/test_contenthost.py -k 'test_satellite_installation'

[Satellite-QE]

trigger: test-robottelo
pytest: tests/foreman/installer/test_installer.py -k test_satellite_installation

[Satellite-QE]

PRT Result

Build Number: 9574
Build Status: SUCCESS
PRT Comment: pytest tests/foreman/installer/test_installer.py -k test_satellite_installation --external-logging
Test Result : ========== 1 passed, 19 deselected, 32 warnings in 1897.18s (0:31:37) ==========