cmd/rofl: Fix external service volumes check

[matevz]

Existing behavior didn't allow implicit volumes with default settings, for example

services:
  ollama:
    image: "docker.io/ollama/ollama"
    ports:
      - "11434:11434"
    volumes:
      - ollama-storage:/root/.ollama
    entrypoint: ["/usr/bin/bash", "-c", "/bin/ollama serve & sleep 5; ollama pull ${OLLAMA_MODEL}; wait"]

volumes:
  ollama-storage:

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