Geo Ip configuration dialog stuck after initially specifying invalid file

## Expected Behavior

When configuring the Geo-Location Processor Configuration, I should be able to disable it again after having specified an invalid geo ip database file.

## Current Behavior

When enabling the geo ip processor in System -> Configurations and clicking on "Update configuration" for the default settings, the dialog is stuck in something like a validation loop. It is still possible to disable the checkbox again, but the buttons will stay disabled. The only option to leave the dialog is to "cancel" it by clicking outside of it.


## Possible Solution

## Steps to Reproduce (for bugs)

1. Go to "Systems" -> "Configuration" -> "Plugins" -> "Geo-Location Processor"
2. Click on "Edit configuration"
3. Check "Enable Geo-Location processor"
4. Point database files to non-existing locations
5. Click on "Update configuration"

## Context

## Your Environment

* Graylog Version: Graylog 5.1.0-beta.1
* Java Version:
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: