fix: configure minio-init as service_completed_successfully in compose

The minio-init init container exits after completing its setup task (exit 0).
Configure it in aether-runner's depends_on with service_completed_successfully
so docker compose up --wait doesn't treat the exit as a failure.

Author: trobanga

.github/test/minio/compose.yaml

@@ -1,32 +1,28 @@
 name: minio
 
 services:
-  # MinIO S3-compatible object store for S3 upload E2E testing
+  # MinIO S3-compatible object store for S3 upload E2E testing.
+  # Starts the server, creates the test bucket, then stays running.
   minio:
     image: minio/minio:RELEASE.2025-01-20T14-49-07Z
     ports: [ ":9000", ":9001" ]
     networks: [ "aether" ]
     environment:
       MINIO_ROOT_USER: minioadmin
       MINIO_ROOT_PASSWORD: minioadmin
-    command: server /data --console-address ":9001"
+    entrypoint:
+      - /bin/sh
+      - -c
+      - |
+        minio server /data --console-address ":9001" &
+        until mc ready local 2>/dev/null; do sleep 1; done
+        mc alias set local http://localhost:9000 minioadmin minioadmin
+        mc mb --ignore-existing local/aether-test
+        echo "Bucket aether-test created"
+        wait
     healthcheck:
       test: [ "CMD", "mc", "ready", "local" ]
       interval: 5s
       timeout: 5s
       retries: 5
       start_period: 10s
-
-  # Init container that creates the test bucket on startup
-  minio-init:
-    image: minio/mc:RELEASE.2025-01-17T23-25-50Z
-    networks: [ "aether" ]
-    depends_on:
-      minio:
-        condition: service_healthy
-    entrypoint: >
-      /bin/sh -c "
-      mc alias set local http://minio:9000 minioadmin minioadmin &&
-      mc mb --ignore-existing local/aether-test &&
-      echo 'Bucket aether-test created'
-      "