roles: Fix ansible-lint warning on var-naming.

ansible-lint warns if set_fact sets a variable where the name is used
or can be as a parameter for the role.

roles/ipabackup/tasks/copy_backup_to_server.yml

@@ -9,23 +9,23 @@
 
 - name: Set controller source directory
   ansible.builtin.set_fact:
-    ipabackup_controller_dir:
+    __derived_controller_dir:
       "{{ ipabackup_controller_path | default(lookup('env', 'PWD')) }}"
 
 - name: Set ipabackup_item
   ansible.builtin.set_fact:
-    ipabackup_item:
+    __derived_item:
       "{{ ipabackup_name | regex_search('.*_(ipa-.+)', '\\1') | first }}"
   when: "'_ipa-' in ipabackup_name"
 
 - name: Set ipabackup_item
   ansible.builtin.set_fact:
-    ipabackup_item: "{{ ipabackup_name }}"
+    __derived_item: "{{ ipabackup_name }}"
   when: "'_ipa-' not in ipabackup_name"
 
 - name: Stat backup to copy
   ansible.builtin.stat:
-    path: "{{ ipabackup_controller_dir }}/{{ ipabackup_name }}"
+    path: "{{ __derived_controller_dir }}/{{ ipabackup_name }}"
   register: result_backup_stat
   delegate_to: localhost
   become: no
@@ -35,10 +35,10 @@
     msg: "Unable to find backup {{ ipabackup_name }}"
   when: result_backup_stat.stat.isdir is not defined
 
-- name: Copy backup files to server for "{{ ipabackup_item }}"
+- name: Copy backup files to server for "{{ __derived_item }}"
   ansible.builtin.copy:
-    src: "{{ ipabackup_controller_dir }}/{{ ipabackup_name }}/"
-    dest: "{{ ipabackup_dir }}/{{ ipabackup_item }}"
+    src: "{{ __derived_controller_dir }}/{{ ipabackup_name }}/"
+    dest: "{{ ipabackup_dir }}/{{ __derived_item }}"
     owner: root
     group: root
     mode: u=rw,go=r