[BUGFIX] Fix failing test caused by vfs removal

With #74882 usage of vfs was reduced in unit tests, revealing
side effects when tests relied on each other to create
files or folders. Now they need to take care on their own
and clean up behind.
This is one of the missed cases where a test still relied on
a test directory being created.

The test now creates and removes the required assets themself.

Resolves: #97801
Related: #97742
Releases: main
Change-Id: I55611415b89e6b43431cbc8eec2264608c6dfc75
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74970


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>