refactor(NGINX): auto-load certificates

- use container-bound certificates by default
- do not use separate certificate loading include

build/sites/05-secured.conf.disabled

@@ -30,9 +30,6 @@ server {
     listen 443 ssl http2;
     include /etc/nginx/server_names.conf;
 
-    # ssl certificates
-    include /etc/nginx/ssl_certs.conf;
-
     location / {
         try_files $uri $uri/ =404;
     }