[TASK] Fix closure comparison in test

ExactValueMatching of Closures in Prophecy may
result in Comparison Failures causing the test
to fail in newer PHPUnit Versions. Instead of
an exact match of that closure, a type comparison
is enough - as calling the closure is tested via
following assertions.

Resolves: #89982
Releases: master, 9.5
Change-Id: I23ef94a291a07d02e0c8857a1aeaf14931406af0
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62737


Tested-by: Jan Stockfisch <typo3@jan-stockfisch.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Jan Stockfisch <typo3@jan-stockfisch.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>