[Eval > Trends] Trends tab displays data for deleted runs with broken navigation links

## EPAM AI DIAL Admin version
Admin: [FE]0.21.0-dev.167 [BE]0.21.0-dev.11

## How to reproduce
1. Login to Admin. Open any Test Suite that has completed runs.
2. Go to the Trends tab - note the run count (e.g. "10 Runs").
3. Go to the Runs tab and delete all runs in the suite.
4. Return to the Trends tab.
5. Hover over any data point in the "Overall score trend" or "Metric Trends" chart.

## Actual result
The Trends tab continues to display historical data for the deleted runs (KPI cards, Overall score trend chart, and Metric Trends all retain values). The tooltip on each chart data point shows the run UUID as a clickable link that leads to a 404 page.

## Expected result
Deleted run references should not produce broken navigation. Either the Trends data is updated to exclude deleted runs, or run links in chart tooltips are rendered as plain non-clickable text when the run no longer exists.

## Additional information
Runs and run results are stored in two separate data sources. Deleting a run via the Runs tab does not remove the underlying analytics results. Cascading deletes are not currently feasible due to a planned migration to columnar storage, which penalizes deletions by design. The correct resolution requires an architectural decision.

## Confidential information
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