apt-get install breaks the test runner

[picnoir]

Describe the bug

The apt-get install output sometimes breaks the NixOS test runner. I think it's related to the apt menu. The current (terrible) workaround consists in redirecting the apt-get output to a file.

I don't have a minimal reproducer yet.

[picnoir]

@Mic92 suggests to get rid of the current backdoor service in favor of something like https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/vm_tools/vsh/README.md

Would make sense to upstream this to the NixOS test runner if we go that route.