Refactor async task handling

- Standardize async/poll usage with 'ASYNC_ENABLED | bool'
- Add async/poll parameters to Cloudflare, Nginx, Mailu, MIG, Nextcloud, and OpenLDAP tasks
- Update async configuration in 'group_vars/all/00_general.yml' to ensure boolean evaluation
- Allow CAA, cache, and DNS tasks to run asynchronously when enabled

https://chatgpt.com/share/689cd8cc-7fbc-800f-bd06-a667561573bf

roles/srv-web-7-4-core/tasks/01_core.yml

@@ -47,9 +47,12 @@
     mode:  '0755'
   loop: >
     {{ nginx.directories.data.values() | list }}
+  async: "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
+  poll:  "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"
   
 - name: "Include tasks to create cache directories"
   include_tasks: 03_cache_directories.yml
+  when: run_once_nginx_reverse_proxy is not defined
 
 - name: create nginx config file
   template: