Aggregation: Daylight Saving switch is visible in Charts

## Expected Behavior
A chart with percentages should not go above 100%. For example, when displaying the humidity.

## Current Behavior
When we switch away from Daylight saving time, we present the chart with doubled values:

## Your Environment
* Graylog Version: 7.0

## Checklist
[x] This issue fix need to be backported.
[] Does this issue have **security** implications?