CI: Switch to plain Alpine image with modern ansible-lint

This also enables GitLab-parseable ansible-lint output.

Cf. common!26 (merged)

This also removes two unsupported and obsolete roles, as well as fixing a few (minor) issues along the way.

desktop/handlers/main.yml

 ---
-# file: roles/client/handlers/main.yml
 
 - name: update apt cache
-  apt: update_cache=yes
+  apt:
+    update_cache: true
 
 - name: restart sddm
-  service: name=sddm state=restarted
+  service:
+    name: sddm
+    state: restarted
 
 - name: reload systemd service files
-  systemd: daemon_reload=yes
+  systemd:
+    daemon_reload: true