Remove confirmation when deleting Widgets in 3.2

## What?
In 3.2 it needs to be confirmed every time when a widget is deleted.

## Why?
Deleting widgets in 3.2 is already a two-step process so adding an extra confirmation is only making Graylog more inefficient with very little benefit since it is difficult to accidentally delete a widget and even then it's not the end of the world if actually a widget was accidentally deleted.

Also - besides the inefficiency - when narrowing down search results with constantly adding and removing aggregations it can be quite annoying to having to confirm every time.

## Your Environment
* Graylog Version: 3.2