Correlations: Loki link only shows up if corresponding derived field is added

### What happened? <img width="858" height="412" alt="Image" src="https://github.com/user-attachments/assets/e998a9b1-58ca-4a8c-a945-a47f4dd346c7" /> Correlations link/button only shows up if a derived field adds the label that the correlation is looking for. I also don't expect that the button shows up next to the `traceid` in the `Links` section, I'd expect it to show up next to the `traceid` in the `Fields` section. ### What did you expect to happen? I expect the correlations link/button to show up on the field in the `Fields` list if it is present. ### Did this work before? Not sure, first time trying out correlations. ### How do we reproduce it? 1. Create a correlation with a source of `loki`, a target of `tempo`, and a `Results field` of $FOO <img width="663" height="303" alt="Image" src="https://github.com/user-attachments/assets/3136a2ae-fce8-49cd-9ed9-ef05e82c8752" /> <img width="549" height="398" alt="Image" src="https://github.com/user-attachments/assets/aac81270-678a-4cab-8f18-c82a68907b73" /> <img width="667" height="423" alt="Image" src="https://github.com/user-attachments/assets/2d7d33c9-1a38-4520-b98c-ab1f027fed93" /> 2. View some Loki logs 3. Observe that the button does not show up despite the field being present 4. Add a derived field with a `name` that matches $FOO 5. Observe that the button now shows up besides the button for the derived field <img width="888" height="335" alt="Image" src="https://github.com/user-attachments/assets/fb7b0dcb-625d-4aae-b201-5982b9dce48d" /> ### Is the bug inside a dashboard panel? No, it can be triggered through Explore. ### Environment (with versions)? Grafana: Grafana v12.0.2 (5bda17e7c1) OS: macOS Sequoia 15.4 Browser: Chrome 137.0.7151.120 ### Grafana platform? Docker ### Datasource(s)? Loki