fix ansible-lint warnings of knot role

roles/knot/tasks/03-configure-exporter.yaml

@@ -1,7 +1,7 @@
 - name: Deploy knot-exporter systemd unit
   tags: [ auth-dns ]
   become: true
-  register: deploy_service_file
+  register: knot_deploy_service_file
   notify: restart knot-exporter
   ansible.builtin.template:
     src: knot-exporter.service.j2
@@ -17,5 +17,4 @@
     name: knot-exporter.service
     state: started
     enabled: true
-    daemon_reload: "{{ deploy_service_file.changed }}"
-
+    daemon_reload: "{{ knot_deploy_service_file.changed }}"