Fix issues reported by ansible-lint (var prefixes)

playbooks/roles/lego/tasks/systemd.yml

@@ -16,7 +16,7 @@
   ansible.builtin.shell:
     executable: /usr/bin/bash
     cmd: "set -o pipefail && systemctl list-timers 'lego@*' --all --output=json | jq -r '.[].unit'"
-  register: systemd_timers_result
+  register: lego_systemd_timers_result
   changed_when: false
 
 - name: Generate systemd timer names
@@ -28,7 +28,7 @@
     name: "{{ item }}"
     state: stopped
     enabled: false
-  loop: "{{ systemd_timers_result.stdout_lines | difference(lego_systemd_timers) }}"
+  loop: "{{ lego_systemd_timers_result.stdout_lines | difference(lego_systemd_timers) }}"
   become: true
 
 - name: Enable the system timers