[TASK] Remove array items to perform string comparison

The Fluid IfViewHelper doesn't need any longer array items to perform
string comparison.
The patch removes all occurences in extensionmanager sysext.

Resolves: #46995
Releases: 6.1
Change-Id: If533afd4d0f4522b3455e308a7f01969f4fb0326
Reviewed-on: https://review.typo3.org/19691
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring