Improve errors/exceptions when index is cycled in flood stage on ES7

## Expected Behavior

## Current Behavior

When an index is cycled while ES is in flood stage on ES7, lots of exceptions are happening. Although most operations are retried after flood stage, this is creating lots of noise in Graylog's output that should be avoided.

## Possible Solution

## Steps to Reproduce (for bugs)

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## Context

## Your Environment

* Graylog Version:
* Java Version:
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: