Show specific transaction/span names being caught by inbound filters

### Problem Statement

When transactions or spans are filtered (e.g., by the "Filter out health check transactions" setting), users can only see aggregate counts by filter reason in the Data Filters chart. There's no way to see which specific transaction names are being filtered.

This makes it difficult to:
- Verify that the filter is correctly catching health checks (like /health, /ping) and not something else
- Debug cases where legitimate transactions might be incorrectly triggering a filter
- Understand why a large percentage of data is being filtered

Users have reported spending significant time debugging filtering issues because they can see "Filtered Transaction: 17,913" but have no visibility into what those 17,913 transactions actually are.

### Solution Brainstorm

- Add a drill-down view from the Data Filters chart that shows a sample/list of filtered transaction names grouped by filter reason
- Add a "Filtered" tab or section in the Stats page that lists top transaction names being filtered
- Show recent examples of filtered transaction names in the filter settings UI so users can verify the filter is working as expected

### Product Area

Settings

Start by reviewing the Data Filters chart, Stats page, and filter settings UI described in the issue. Define how filtered transaction names should be exposed and grouped or sampled by filter reason; done means users can inspect representative names and distinguish expected health checks from unintended filtering.

Written by the indexing model from the issue text.