fix: add -peers=none to master command for standalone mode

- Ensures master runs in standalone single-node mode
- Prevents master from trying to form a cluster
- Required for proper initialization in test environment

test/java/spark/docker-compose.yml

@@ -8,7 +8,7 @@ services:
     ports:
       - "9333:9333"
       - "19333:19333"
-    command: "master -ip=seaweedfs-master -ip.bind=0.0.0.0"
+    command: "master -ip=seaweedfs-master -ip.bind=0.0.0.0 -peers=none"
     networks:
       - seaweedfs-spark