Refactor async execution handling across LDAP and Nextcloud roles

- Introduce global async configuration in group_vars/all/00_general.yml:
  - ASYNC_ENABLED (disabled in debug mode)
  - ASYNC_TIME (default 300s, omitted if async disabled)
  - ASYNC_POLL (0 for async fire-and-forget, 10 for sync mode)
- Replace hardcoded async/poll values with global vars in:
  - svc-db-openldap (03_users.yml, 04_update.yml)
  - web-app-mig (02_build_data.yml)
  - web-app-nextcloud (03_admin.yml, 04_system_config.yml, 05_plugin.yml,
    06_plugin_routines.yml, 07_plugin_enable_and_configure.yml)
- Guard changed_when and failed_when conditions to only evaluate in synchronous
  mode to avoid accessing undefined rc/stdout/stderr in async runs

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

group_vars/all/00_general.yml

@@ -64,6 +64,11 @@ LETSENCRYPT_LIVE_PATH:                    "{{ LETSENCRYPT_BASE_PATH }}live/"
 DOCKER_RESTART_POLICY:                    "unless-stopped"
 DOCKER_VARS_FILE:                         "{{ playbook_dir }}/roles/docker-compose/vars/docker-compose.yml"
 
+# Asyn Confitguration
+ASYNC_ENABLED:  "{{ not MODE_DEBUG | bool}}"            # Activate async, deactivated for debugging
+ASYNC_TIME:     "{{ 300 if ASYNC_ENABLED else omit }}"  # Run for mnax 5min
+ASYNC_POLL:     "{{ 0 if ASYNC_ENABLED else 10 }}"      # Don't wait for task
+
 # default value if not set via CLI (-e) or in playbook vars
 allowed_applications: []