[TASK] Avoid misusing csv file of different test in ImageViewHelperTest

This is a follow-up patch for #102220. A dedicated fileadmin path has
been added for ImageViewHelperTest and unnecessary fixtures are removed.

In addition, error message checks are added for the invalidArgument
test cases in order to clarify, what exactly is supposed to go wrong.

Resolves: #102221
Related: #102220
Releases: main, 12.4
Change-Id: I03404c5f15f1a67032fce01febc4a9a5214373f6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81462


Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Nikita Hovratov <nikita.h@live.de>