[TASK] gitlab-ci: Backup TYPO3 logs of backend acceptance tests

Sometimes acceptance tests fail due to a failed TYPO3 backend request,
which is recorded in the TYPO3 log file. Save this log file along with
the Acceptance Reports folder in the gitlab-ci job artifacts.

Resolves: #94843
Releases: master, 10.4, 9.5
Change-Id: I0b260c197a6a71dc23e6f9da547fc20a55fc4ce7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70497


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>