`events_created` metrics are unclear

## Current Behavior

When reviewing metrics for `events_created` either in the UI or the Prometheus endpoint, it's unclear what these metrics actually refer to:

```
# HELP gl_event_processor_events_created_total Generated from Dropwizard metric import (metric=org.graylog.events.processor.aggregation.AggregationEventProcessor.5faef5de3f94ee72d0a8c0e0.events_created, type=com.codahale.metrics.Meter)
# TYPE gl_event_processor_events_created_total counter
gl_event_processor_events_created_total{node="00d2902d-a2ab-4e9c-8e49-571ce91d269c",processor_id="5faef5de3f94ee72d0a8c0e0",type="aggregation",} 875283.0
gl_event_processor_events_created_total{node="00d2902d-a2ab-4e9c-8e49-571ce91d269c",processor_id="60d386c12eb0c235245d38e2",type="aggregation",} 3067.0
gl_event_processor_events_created_total{node="00d2902d-a2ab-4e9c-8e49-571ce91d269c",processor_id="60d5edb69e7daa03e6fe806e",type="aggregation",} 0.0
gl_event_processor_events_created_total{node="00d2902d-a2ab-4e9c-8e49-571ce91d269c",processor_id="60d386c12eb0c235245d38e6",type="correlation",} 1111.0
```

## Expected Behavior

In an ideal world, I'd expect to be able to have metrics that have additional context to them that makes it so I don't have to try and suss out what the ID refers to.

## Possible Solution

What would provide more clarity would be either some additional labels in Prometheus to provide a metric that's more easily understood by Graylog operators, or adjust the name to be more human-understandable when generating the metrics in the UI.

## Context

The goal I'm trying to accomplish is to have visibility into what's going on inside of my Graylog deployment. When IDs are involved instead of human-readable references, this results in a lot of back and forth with API calls and writing Prometheus rewrite rules--it's not sustainable and I imagine that for our users and customers, this experience is less than ideal.

## Your Environment

* Graylog Version: 4.1.3
* Java Version: 1.8
* Elasticsearch Version: 7.10.2
* MongoDB Version: 4.0
* Operating System: Ubuntu 20.04
* Browser version: https://www.whatsmybrowser.org/b/OL01S