[BUGFIX] Remove hardcoded calling script in help controller

The Extbase help command controller has the calling
script hardcoded in several places. This may cause
confusion if the calling script was different.

Use the real script from argv[0] instead.

Resolves: #58456
Releases: 6.2
Change-Id: I622484cb75ad87078ed8b5f923f1f3b972c64124
Reviewed-on: https://review.typo3.org/29809
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring