bootstrap, dea_base, nailgun: Pin 4.8.0-43 kernel
Since newer kernels have issues with AAVMF + vhost_net,
we need to also temporarily blacklist vhost_net.
NOTE: This change also adds linux-image-extra packages to both x86_64
and AArch64 target image(s).
TODO: Remove vhost_net blacklist (later).
JIRA: ARMBAND-161
JIRA: ARMBAND-171
JIRA: ARMBAND-227
JIRA: ARMBAND-230
JIRA: ARMBAND-239
JIRA: ARMBAND-244
Change-Id: I456f4235d04375905df9d6f776b84f2e0eee22d6
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>