Give search-input correct padding-right value

## What does this MR do?
This fixes how `padding-right: 20px` was being applied to the style rule of `.search-input`, preventing text in that form from clipping through `.search-icon`

## Are there points in the code the reviewer needs to double check?
If there are any cases where `.search .search-input` is used in a search form where there is no right-side icon (I could not find such occurrence myself).

## Why was this MR needed?
Some text in long search queries were being hidden by the close icon being used in the search form. This makes it a bit more presentable. ;)

## Screenshots (if relevant)
__Before__
![before](/uploads/2757a6264a1d2053af7212f72df7c3f9/before.png)

__After__
![after](/uploads/322fbfa08594f0f33d10a3226c82326d/after.png)

See merge request !7407