Searching the complete filesystem with grep seems to be a bit tricky but on partly searches I found the string in the file /var/lib/dpkg/info/grub-pc.templates but "dpkg -S" doesn't show a package for it so maybe it is a generated file.
Searching the complete filesystem with grep seems to be a bit tricky but on partly searches I found the string in the file /var/lib/ dpkg/info/ grub-pc. templates but "dpkg -S" doesn't show a package for it so maybe it is a generated file.