[TASK] Change input type for backend search result limit to "number"

This changes the html input type for the backend search result limit
from "text" to the html5 attribute "number".

Releases: master
Resolves: #61778
Change-Id: I28aac40a61e6d6499cd6aa72beda5bb765c25d01
Reviewed-on: http://review.typo3.org/32904
Reviewed-by: Stefan Froemken <froemken@gmail.com>
Tested-by: Stefan Froemken <froemken@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>