[TASK] Documentation: Update jQuery-usage

* Use central jQuery
* Get rid of not used JS-parts (tools, validation)

Change-Id: Ie64b66fd0f6cc5a73c8dc70425fb18aa74b6d8be
Resolves: #52932
Releases: 6.2
Reviewed-on: https://review.typo3.org/24879
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters