Add observability for webhooks filtered out or with failed filtering
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=592027) </details> <!--IssueSummary end--> The following discussion from !224355 should be addressed: > **thought**: one thing I noticed is that `FilterEvaluator.evaluate` rescues all `StandardError` and returns `false`, which means in case of an error the webhook is silently skipped and there is no `WebHookLog` entry for the user. While this error path is unlikely to be hit today (since filters can only be set via Rails console manually), it could become a real concern when the API/UI is introduced. > > Something to consider for the follow-up is also adding observability (e.g., `ErrorTracking.track_exception`, metrics).
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