[Symfony 6] The Drupal\Tests\jsonapi\Kernel\EventSubscriber\ResourceObjectNormalizerCacherTest fails with Symfony 5

Problem/Motivation

Drupal\Tests\jsonapi\Kernel\EventSubscriber\ResourceObjectNormalizerCacherTest fails with Symfony 5 with the following message:

rupal\Tests\jsonapi\Kernel\EventSubscriber\ResourceObjectNormalizerCacherTest::testLinkNormalizationCacheability
Prophecy\Exception\Doubler\ClassMirrorException: Could not reflect class Symfony\Component\HttpKernel\Event\TerminateEvent as it is marked final.

Proposed resolution

Mocking or prophesizing final classes is impossible, therefor create an instance of the class and use that in testing.

Remaining tasks

TBD

User interface changes

None

API changes

None

Data model changes

None

Release notes snippet

None