feat: load oss media config from sys config

docker/tinode/Dockerfile.build

@@ -91,7 +91,7 @@ ENV ADMIN_INTERNAL_API_TIMEOUT_MS=3000
 # DB routing resolves to the same tinode DB for the seeded "default" tenant.
 ENV TENANT_REGISTRY_DB=hotgo
 
-ENV MEDIA_HANDLER=fs
+ENV MEDIA_HANDLER=sys_config
 ENV FS_CORS_ORIGINS='["*"]'
 ENV AWS_CORS_ORIGINS='["*"]'
 ENV SMTP_HOST_URL='http://localhost:6060'