[TASK] Clean up TimeTracker usage in frontend requests

For historical purposes, TimeTracker->push() is
called with an empty string in the second parameter,
however, as this parameter is optional and set to ''
by default as well, the code readability can be improved
by just using the first parameter when using
TimeTracker->push()

Resolves: #84964
Releases: master
Change-Id: I37a338268f9b2df9f2a98414075d207b63dc542e
Reviewed-on: https://review.typo3.org/56913


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>