Pipeline Rule Builder: Unintuitive checkbox behavior

## What?
When using the pipeline rule builder and the rule function has a boolean, we show a checkbox:

The user expects that the label false indicates that when checking the box, the value will be `false`. But
after clicking the checkbox:

The label changes to `true`.

## Why?
This is quite unexpected behavior and cannot be found in any other web app or even inside of Graylog.

## Your Environment
* Graylog Version: Graylog Cloud 6.1.8 (589)