Drilldown > Traces: error/empty-state icon is misaligned when the data source is missing (Grafana 12.x)

### What happened? <img width="1917" height="751" alt="Image" src="https://github.com/user-attachments/assets/bf9dfee6-51de-4ec4-9f0a-704949c87e89" /> ### What did you expect to happen? The error/empty-state icon should be positioned consistently inside the panel frame (top-left within the panel header/content area), with the same padding/margins used by panel alerts elsewhere in Grafana. No overlap with panel borders or neighboring tiles. ### Did this work before? Not sure for that. ### How do we reproduce it? 1. Start a clean Grafana 12.x. Example: docker run -p 3000:3000 grafana/grafana:12.x 2. Do not configure any trace data source (Tempo/Jaeger). 3. Navigate to: Drilldown > Traces. 4. Ensure the Data source selector is empty or points to a non-existent/removed data source. 5. Observe the “No data” tiles and the error indicator icon. ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? Grafana: 12.x (latest at the time of reporting) Edition: Grafana OSS Browser: Chrome 142.0.7444.60 ### Grafana platform? Kubernetes ### Datasource(s)? _No response_