fix(web-app-nextcloud): set trusted_proxies through occ only

The env file carried TRUSTED_PROXIES joined on spaces next to the occ
config:system:set of trusted_proxies in vars/system.yml, which writes
the same NEXTCLOUD_TRUSTED_PROXIES list as JSON on every stack-host
deploy. The image's reverse-proxy.config.php only overrides config.php
when the variable is set, so dropping it leaves one source with the same
value and satisfies test_env_value_space_quoted, which flagged the
unquoted space join after the feature/updater merge.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

roles/web-app-nextcloud/templates/env.j2

@@ -27,7 +27,6 @@ NEXTCLOUD_ADMIN_PASSWORD={{ NEXTCLOUD_ADMINISTRATOR_PASSWORD | dotenv_quote }}
 NEXTCLOUD_INIT_GATE_USER={{ NEXTCLOUD_DOCKER_USER }}
 
 NEXTCLOUD_TRUSTED_DOMAINS={{ NEXTCLOUD_DOMAIN }}
-TRUSTED_PROXIES={{ NEXTCLOUD_TRUSTED_PROXIES | join(' ') }}
 OVERWRITECLIURL={{ NEXTCLOUD_URL }}
 
 REDIS_HOST={{ lookup('engine', 'redis', application_id, 'host') }}