[TASK] Strictify UnitTests part 8

Strictifies the following extensions:

- EXT:dashboard
- EXT:extbase

Resolves: #94897
Releases: master
Change-Id: I1cb8c2ebdc4c0c73a26754163e99f5bffd0520a3
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70632


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>