Chore: Use a local http server instead of external to reduce flakiness (#11916)

docker/compose/docker-compose.ci-test.yml

@@ -34,3 +34,13 @@ services:
     ports:
       - "3143:3143" # IMAP
     restart: unless-stopped
+  nginx:
+    image: docker.io/nginx:1.29-alpine
+    hostname: nginx
+    container_name: nginx
+    ports:
+      - "8080:8080"
+    restart: unless-stopped
+    volumes:
+      - ../../docs/assets:/usr/share/nginx/html/assets:ro
+      - ./test-nginx.conf:/etc/nginx/conf.d/default.conf:ro

docker/compose/test-nginx.conf

@@ -0,0 +1,14 @@
+server {
+    listen 8080;
+    server_name localhost;
+
+    root /usr/share/nginx/html;
+
+    # Enable CORS for test requests
+    add_header 'Access-Control-Allow-Origin' '*' always;
+    add_header 'Access-Control-Allow-Methods' 'GET, HEAD, OPTIONS' always;
+
+    location / {
+        try_files $uri $uri/ =404;
+    }
+}