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 test_env_value_space_quoted on feature/store-i18n no longer flags the unquoted space join after the next updater merge.

Same removal as bcde3550c8 on feature/store-i18n, landed on the updater line it came from. A fresh compose full_cycle deploy of web-app-nextcloud without the line kept trusted_proxies at the three proxy hops through occ alone, with both passes green.

Co-Authored-By: Claude Opus 5.5 (1M context) <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 }}
 OVERWRITEPROTOCOL={{ NEXTCLOUD_PROTOCOL }}