[TASK] Remove systemLogLevel example in Router.ts

This example configuration was accidentally added by a later commit
after it was already removed.

Resolves: #93600
Related: #89645, #89740
Releases: master, 10.4
Change-Id: I79bbbf3210e67e0f5425563ba58765115db3cd12
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/68139


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>