Rename async job variables for consistency

Rename async job variables in UFW and upgrade roles to follow a
consistent
naming pattern (upgrade_<os>_job) for better maintainability.

roles/ufw/tasks/main.yml

@@ -18,11 +18,11 @@
 - name: Add UFW to default runlevel (Alpine)
   ansible.builtin.command:
     cmd: rc-update add ufw default
-  register: rc_update_result
-  changed_when: >- # ">- : transform multiple lines into one line"
-    'already' not in rc_update_result.stdout
-    and 'already' not in rc_update_result.stderr
-  failed_when: rc_update_result.rc != 0
+  register: ufw_rc_update_result
+  changed_when: >- # " >- : transform multiple lines into one line"
+    'already' not in ufw_rc_update_result.stdout
+    and 'already' not in ufw_rc_update_result.stderr
+  failed_when: ufw_rc_update_result.rc != 0
   when: ansible_facts['os_family'] == "Alpine"
 
 - name: Set default incoming policy