`WebHookWorker` is currently experiencing ~12k unhandled errors per
week.

This MR handles the following errors:

- `EOFError`: `EOFError` can be due to using port 443 without SSL, or
   transient network failures. The SSL configuration problem is unlikely
   because `HTTParty` handles setting this, so it's like this error is
   due to the remote server terminating the connection.
- `ActiveRecord::RecordNotFound`
- `Errno::ENETUNREACH`: handled the same as `Errno::EHOSTUNREACH` is, in
  `Gitlab::HTTP`.

https://gitlab.com/gitlab-org/gitlab/-/issues/337708

Changelog: fixed