make use of preinstalled variable

roles/jitsimeet/tasks/prepare_system.yml

@@ -6,16 +6,17 @@
       DefaultLimitNPROC=65000
       DefaultTasksMax=65000
 
-- name: jitsimeet | reload systemd
+- block
+  - name: jitsimeet | reload systemd
     systemd:
       daemon_reload: true
 
-- name: jitsimeet | import GPG key
+  - name: jitsimeet | import GPG key
     apt_key:
       url: "https://download.jitsi.org/jitsi-key.gpg.key"
       state: present # not required. choices: absent;present. Ensures that the key is present (added) or absent (revoked).
 
-- name: jitsimeet | add repository
+  - name: jitsimeet | add repository
     lineinfile:
       path: "/etc/apt/sources.list.d/jitsi-stable.list"
       line: "deb https://download.jitsi.org stable/"
@@ -23,10 +24,11 @@
       backup: True
     notify: apt_update
 
-- name: jitsimeet | flush handlers
+  - name: jitsimeet | flush handlers
     meta: flush_handlers
 
-- name: jitsimeet | add debconf-utils package
+  - name: jitsimeet | add debconf-utils package
     package:
       name: debconf-utils
       state: latest
+  when: preinstalled == false or preinstalled is not defined