No Clear Button for the Search Filter Field

## What?

On the Search page, the field nest to the green magnifier that allows entry of the search filter does not have a button to clear that field. In order to clear the field, you either have to Reset the entire search (which wipes out all the other customization) or use the mouse to navigate to the field, select and delete the contents then click the green magnifier to update. Doesn't seem like alot but it take alot of time when one is performing many filters.

## Why?

Just slows users down and they expect a small X on the far right of the field to clear the field.


## Your Environment

* Graylog Version: Graylog 6.2.0-rc.1+a672433
* OpenSearch Version:
* MongoDB Version:
* Operating System:
* Browser version: