Refactor: Run kolibri migrations task

Run kolibri migrations as part of the kolibri setup itself. This makes
kolibri.service initial run faster on low-end Raspberry Pi devices.

"Unable to start service kolibri: Job for kolibri.service failed because
a timeout was exceeded." #1158

https://github.com/iiab/iiab/issues/1158

roles/kolibri/tasks/main.yml

@@ -29,8 +29,8 @@
     extra_args: --no-cache-dir
   when: internet_available
 
-- name: Set kolibri default language
-  shell: export KOLIBRI_HOME="{{ kolibri_home }}" && "{{ kolibri_exec_path }}" language setdefault "{{ kolibri_language }}"
+- name: Run kolibri migrations
+  shell: export KOLIBRI_HOME="{{ kolibri_home }}" && "{{ kolibri_exec_path }}" manage migrate
   ignore_errors: yes
   when: kolibri_provision