sdk-debos-image-building: Remove kvm_intel module

Task https://phabricator.apertis.org/T7879

The goal of this test is to ensure we can execute the getting-started instructions in the apertis-image-recipes README from inside the Apertis SDK running on Virtualbox.

We don't actually have Virtualbox in LAVA, so it must be simulated. As Virtualbox doesn't support nested KVM virtualization, let's remove the KVM module. This should trigger the chroot-based Debos backend instead of the fakemachine one"

v2022 LAVA test job: https://lava.collabora.co.uk/scheduler/job/6535290