[TASK] Remove rel="shortcut" from page.shortcutIcon output

The shortcut link type is invalid and must not be used, see e.g.
https://developer.mozilla.org/en-US/docs/Web/HTML/Link_types

Resolves: #94821
Releases: master
Change-Id: I5b3e5cf594ce5deedafd8b6c66d230a64b22ba58
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70454


Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>