[TASK] Use FluidEmail in SystemStatusUpdateTask

Migrate the mails in SystemStatusUpdateTask to FluidEmails.
As the current content format is rather limited it is not changed
and only plain mails are sent.

Resolves: #90726
Releases: master
Change-Id: I97fc5c01326d9997cacfd56b2b917e79fe0688d4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63725


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Guido Schmechel <guido.schmechel@brandung.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>