[BUGFIX] Namespace usage in test

Patch for issue #31998 introduced a namespace in unit test,
the test suite now fails after patch for issue #53682. Use
old class name instead.

Change-Id: I83e7cd33787364c1f531c51406f09884aff418c6
Resolves: #55811
Related: #53682
Related: #31998
Releases: 4.7, 4.5
Reviewed-on: https://review.typo3.org/27513
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn