[TASK] runTests.sh: Remove .csv integrity handling

When core functional tests started to heavily rely
on CSV based import- and assertion files, we found
that editing such .csv files in Microsoft Excel leads
to warnings if the number of columns is not identical
for each row.

Script checkIntegrityCsvFixtures.php has then been
established to verify all rows of .csv fixture files
have the same amount of fields per file, and has been
enabled as CI job to ensure all existing fixture
files follow this.

Nowadays, this restriction feels archaic: Devs actively
working with these CSV files typically edit them in
an IDE like PhpStorm directly and don't use Excel for
this anymore. The PhpStorm plugin "Rainbox CSV" also
helps by coloring these files and other alternatives
like libreoffice do not have this 'all rows must have
same number of colums' restriction.

The patch drops the script, the runTests.sh usage and
the CI calls. This has the additional advantage that
line breaks for single fields are now possible, which
will further improve handling and readability of field
values in upcoming patches.

Resolves: #97274
Related: #83943
Releases: main, 11.5, 10.4
Change-Id: I2b4c2afc98c8471bccae1afb15e055182b563ee7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74131


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>