cachegen: Remove remnants of -f option
cachegen: Remove remnants of -f option

The -f option of cachegen was removed in d71c794d.

refs #16211

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc