sdk-debos-image-building: Remove kvm_intel module

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"

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>