Define and implement specs for bootstrap-os (#4455)

* Add README to bootstrap-os role

* Rework bootstrap-os once more

* Document workarounds for bugs/deficiencies in Ansible modules
* Unify and document role variables
* Remove installation of additional packages and repositories
* Merge Ubuntu and Debian tasks
* Remove pipelining setting from default playbooks
* Fix OpenSUSE not running its required tasks

roles/bootstrap-os/tasks/bootstrap-opensuse.yml

@@ -1,13 +1,10 @@
 ---
-- name: Ensure zypper cache is updated (SUSE)
-  zypper_repository:
-    repo: "*"
-    runrefresh: yes
+# OpenSUSE ships with Python installed
 
-- name: Install required packages (SUSE)
-  package:
-    name: "{{ item }}"
+# Without this package, the get_url module fails when trying to handle https
+- name: Install python-cryptography
+  zypper:
+    name: python-cryptography
     state: present
-  with_items:
-    - python-cryptography
+    update_cache: true
   become: true