Use a `-` as a separator to fix issues with already running detection

[vb-linetco]

Summary

Fix an issue where services are wrongly restarted as a corrective measure, due to images built with docker compose not detected as running.

Additional Context

Add any additional context about the problem here.

• [x] Root cause and the steps to reproduce. (If applicable)
• [x] Thought process behind the implementation.

Related Issues (if any)

Fixes #955, for more details see the issue, where this fix already is proposed.

Checklist

• [x] Manually verified. (For example puppet apply)