Convert dynamic includes to static imports

When task/role files are included using include_tasks, tags are not
passed to the included tasks. As a result, tags like sahara-config
do not have the intended effect. This patch changes include_tasks
to import_tasks for all cases where dynamic vars or loops are not used
so that tags are properly handled.

Reference -
https://docs.ansible.com/ansible/latest/user_guide/playbooks_reuse.html
https://bugs.launchpad.net/openstack-ansible/+bug/1815043

Change-Id: I74bda8876e0f043cd7362ab04fcdb74d24d35d72

tasks/main.yml

@@ -57,7 +57,7 @@
     - common-mq
     - sahara-config
 
-- include_tasks: sahara_pre_install.yml
+- import_tasks: sahara_pre_install.yml
   tags:
     - sahara-install
 
@@ -81,24 +81,24 @@
   tags:
     - sahara-install
 
-- include_tasks: sahara_post_install.yml
+- import_tasks: sahara_post_install.yml
   tags:
     - sahara-config
 
-- include_tasks: sahara_uwsgi.yml
+- import_tasks: sahara_uwsgi.yml
   tags:
     - sahara-config
 
-- include_tasks: sahara_init_common.yml
+- import_tasks: sahara_init_common.yml
   tags:
     - sahara-config
 
-- include_tasks: sahara_db_sync.yml
+- import_tasks: sahara_db_sync.yml
   when: inventory_hostname == groups['sahara_all'][0]
   tags:
     - sahara-config
 
-- include_tasks: sahara_service_setup.yml
+- import_tasks: sahara_service_setup.yml
   when: inventory_hostname == groups['sahara_all'][0]
   tags:
     - sahara-config