Builder mode's Metric Dropdown Shows "No Options Found" When Custom Query Parameters Are Configured

[bdschaap]

Exploring a VictoriaMetrics data source in Builder mode within Grafana shows "No Options Found" in the Metric dropdown when "Custom query parameters" are configured. This prevents using the Builder mode to construct queries. However, switching to Code mode and entering a MetricsQL query works.

Steps to reproduce -

1. Add VictoriaMetrics data source to Grafana
2. Configure "Custom query parameters" such as the following - extra_filters[]={cluster_name="mycluster"}
3. Save
4. Explore the data source
5. Notice that the query is in Builder mode by default.
6. The Metric dropdown shows "No Options Found" when you click on it. The expectation is that It should list metrics available similar to how it would work if "Custom query parameters" weren't configured.
7. Switch to Code mode
8. Enter a MetricsQL query and click "Run query".
9. Results are returned as expected.

I'm using Grafana 10.1.5 and victoriametrics datasource plugin 0.4.0.