Add a UI knob to force using prometheus and/or loki as the datasource, for debugging/troubleshooting purpose. It can be in the query options dropdown. It would have 3 possible values:

• Auto (default)
• Loki
• Prometheus

An infotips should explain the difference between them, and clarify that using Prometheus restricts the aggregation & filtering capabilities.

When Loki or Prometheus aren't installed/configured, the corresponding options should be disabled but still visible.