Bug#1088235: autopkgtest-virt-qemu sometimes hangs when installing build dependencies

[Reinhard Tartler]

Curiously, disabling the autopkgtest `builtin-tests` (which strictly 
speaking doesn't even require qemu), makes the package pass in debci:

https://salsa.debian.org/go-team/packages/podman/-/commit/0d29ddc882b313e4a397826a9cbea7fa593f1f8c
What's so special about this particular test?