Metric org.graylog2.outputs.ElasticSearchOutput.writes Reporting 2x value in 6.1.1 vs 6.0.7

Observed while monitoring the Metric `org.graylog2.outputs.ElasticSearchOutput.writes`, its value doubles in size when upgrading from Graylog 6.0.7 to 6.1.1:


Note that the Indexing-rate of OpenSearch during this time does not change (e.g. does not double in-size), which reveals the curious change in value of the Metric `org.graylog2.outputs.ElasticSearchOutput.writes`:


## Expected Behavior

The value of Metric `org.graylog2.outputs.ElasticSearchOutput.writes` to remain the same while the version of Graylog changes.

## Current Behavior

By upgrading from Graylog version 6.0.7 to 6.1.1, the value reported by this metric doubles in size.

## Possible Solution

N/A, not certain of cause.

## Steps to Reproduce (for bugs)

1. Install Graylog 6.0.7.
2. Create input & continuous stream of data.
3. Monitor metric `org.graylog2.outputs.ElasticSearchOutput.writes`. Take note of mean/average value.
4. Upgrade Graylog to 6.1.1.
5. Monitor metric `org.graylog2.outputs.ElasticSearchOutput.writes`. Take note of mean/average value. Observe the value is now suddenly 2x of what it was in version 6.0.7.

## Context

This issue impacts monitoring of a Graylog node by causing inaccurate metric values to be logged.

## Your Environment

* Graylog Version: 6.0.7 & 6.1.1
* Java Version: bundled
* OpenSearch Version: 2.15.0
* MongoDB Version: 6.0.7
* Operating System: Docker
* Browser version: Firefox 131.0.3