[BUGFIX] Do no force int cast of pageUid in f:link.page

Since #81213, the `pageUid` argument is cast to an int. If that
parameter is omitted, pageUid becomes 0. UriBuilder is able to
determine the page uid by itself, but for this, $pageUid must be
null.

Resolves: #81881
Related: #81749
Releases: master
Change-Id: Ibc211775d657d59491beeaf8c6d4e0ff55c5e6ee
Reviewed-on: https://review.typo3.org/53520


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Achim Fritz <af@lightwerk.com>
Tested-by: Achim Fritz <af@lightwerk.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>