[TASK] Drop fluid FailSafe from install tool

Install tool has a fallback layer to a php based template
in case fluid does not work due to broken reflection for
@inject annotations. Since @inject isn't used anymore in
install tool this layer can be dropped now.

Change-Id: Iedf0e9ea75fa105f649324c993963fb29e666607
Resolves: #72724
Related: #55352
Releases: master
Reviewed-on: https://review.typo3.org/45868


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>