stop input on single nodes in a clusters

## Expected Behavior
Be able to stop all inputs on a specific node.

## Current Behavior
You can only stop the inputs on the complete cluster.

## Possible Solutione
Like the "pause processing" on a single node it is needed to stop the inputs on a node.

## Context
If you have a full journal for some reasons on a single node in cluster and you want to drain this quick, the ability from the UI is needed to stop the inputs. Currently you can only write some iptables rules to stop the ingest.

## Your Environment
* Graylog Version: 4.0 / 3.3.9

[Z#844352]