client/docker: enforce waitress' max upload limitations on nginx proxy

This ensures that both NGINX and Waitress are using the same max upload
request body. See #327

client/nginx.conf.docker

@@ -42,7 +42,7 @@ http {
                 return 200;
             }
 
-            client_max_body_size 0;
+            client_max_body_size 1073741824;
 
             gzip on;
             gzip_comp_level 3;