Replace cronjobs with systemd timers

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/756

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/737

I feel like timers are somewhat more complicated and dirty (compared to
cronjobs), but they come with these benefits:

- log output goes to journald
- on newer systemd distros, you can see when the timer fired, when it
will fire, etc.
- we don't need to rely on cron (reducing our dependencies to just
systemd + Docker)

Cronjobs work well, but it's one more dependency that needs to be
installed. We were even asking people to install it manually
(in `docs/prerequisites.md`), which could have gone unnoticed.

Once in a while someone says "my SSL certificates didn't renew"
and it's likely because they forgot to install a cron daemon.

Switching to systemd timers means that installation is simpler
and more unified.

roles/matrix-common-after/tasks/start.yml

@@ -1,6 +1,6 @@
 ---
 
-- name: Deterimne whether we should make services autostart
+- name: Determine whether we should make services autostart
   set_fact:
     matrix_services_autostart_enabled_bool: "{{ true if matrix_services_autostart_enabled|default('') == '' else matrix_services_autostart_enabled|bool }}"
 
@@ -46,7 +46,7 @@
         Try running `systemctl status {{ item }}` and `journalctl -fu {{ item }}` on the server to investigate.
     with_items: "{{ matrix_systemd_services_list }}"
     when:
-      - "ansible_facts.services[item]|default(none) is none or ansible_facts.services[item].state != 'running'"
+      - "item.endswith('.service') and (ansible_facts.services[item]|default(none) is none or ansible_facts.services[item].state != 'running')"
   when: " ansible_distribution != 'Archlinux'"
 
 - block: