[BUGFIX] Follow-up: Fix broken test in CategoryRegistryTest

Since I156528669704004a86243e03f34d3a1af07cdb21 CategoryRegistryTest
is broken, because argument $options of CategoryRegistry::add
is a required array now. But the method throws an exception
if the argument type doesn't match.

Keep argument typing and remove invalid argument exception
(and corresponding unit test).

Resolves: #52910
Related: #52285
Releases: 6.2
Change-Id: If7d8e51f8fcc0cd9bf579186d768c835837787ef
Reviewed-on: https://review.typo3.org/24860
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind