refactor(role): systemctl daemon-reload after copy

Since unit files are now copied to '/etc/systemd/system' we should
make sure that systemd sees the newest version of all unit files
before we attempt to enable a timer unit.

tasks/archlinux-auto-updates.yml

@@ -54,6 +54,13 @@
   notify:
     - 'Reload systemd unit configs'
 
+# Chances are we've just updated systemd unit files in '/etc/systemd/system'. In
+# a second we'll be enabling a timer unit that was among those files we just
+# (potentially) changed. We should flush our handlers now, i.e. 'systemctl
+# daemon-reload' to make sure systemd knows the newest state of our units.
+- name: 'Flush handlers'
+  meta: flush_handlers
+
 - name: 'If Arch Linux enable systemd timer for OS auto-upgrades'
   ansible.builtin.systemd_service:
     name: 'arch-linux-update-and-restart.timer'