[!!!][TASK] Remove StandaloneView from EXT:form EmailFinisher

The EXT:form EmailFinisher provides the possibility
to send emails via the FluidEmail component since
v10. Therefore the StandaloneView alternative is
now removed.

Since FluidEmail is now the only possibility, the
previously integrated "useFluidEmail" switch is
now removed, too.

Resolves: #96149
Related: #92435
Releases: main
Change-Id: Ia3a3009310313eb0b2bbe3593a8a4f1626b30d55
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72386


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>