Custom Filtering Telemetry

### Problem Statement

Sentry provides [custom filters](https://docs.sentry.io/concepts/data-management/filtering/#how-custom-filtering-works) that are applied at the ingestion level and allow you to ignore certain errors or events before they count towards your quota.

However, there is no way to determine which filter worked and how many times. So while this custom filters feature can be used temporarily to reduce noise and prevent ongoing cost overruns, it is not easy to determine which filter was used most often to track exception patterns and fix them.

### Solution Brainstorm

A simple solution would be to add telemetry to this feature that would track the number of matches or filter calls and report this as a counter in the UI.

### Product Area

Ingestion and Filtering