This reverts parts of commit 68d2839e18.
When running the nova playbooks without having "nova_virt_type" set. It
failed with:
"Error when evaluating variable in dynamic parent include path:
 drivers/{{ nova_virt_type }}/nova_compute_{{ nova_virt_type }}.yml.
 When using static imports, the parent dynamic include cannot utilize
 host facts or variables from inventory"
since the above commit. In ansible it's not allowed to call import_tasks
from a playbook which was included via include_tasks using a dynamic
include path. So we're switching back to "include_tasks" for the
affected playbook.
Change-Id: Ia0227886bd2cc59aab6d2861ef4aa9358d160925
Closes-Bug: 1845497