[BUGFIX] Ignore deleted form elements for form's reference count

The usage count of forms in the form module must not count deleted
elements.

Resolves: #92880
Releases: master, 10.4
Change-Id: Ia58c4e28e03ea1caa3b22ba1188d039fcdea69ea
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66709


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Rudy Gnodde <rudy@famouswolf.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Rudy Gnodde <rudy@famouswolf.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>