Dashboards: Too many dashboard links can hide dashboard content

### What happened? If enough dashboard links are added, the dashboard content becomes completely hidden. <img width="1730" height="914" alt="Image" src="https://github.com/user-attachments/assets/ce22a8d0-3df7-43fe-90eb-63f5ad340d28" /> ### What did you expect to happen? This requires a lot of dashboard links, but with the default behavior of adding a dashboard link from settings being dropdown disabled and no filters, this is not too farfetched a scenario for instances with many dashboards. ### Did this work before? No ### How do we reproduce it? 1. Have >1 dashboard 2. Go to a dashboard, settings -> link -> new link -> back to list 3. Go back to dashboard, repeat step 2 until dashboard links cover page, then cannot scroll to dashboard content. ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? Grafana: 11.6.2 OS: Browser: ### Grafana platform? Other ### Datasource(s)? _No response_