grub.cfg: delete option to boot from CD/DVD

it's confusing, broken and most people nowadays don't use optical drives

it's not even possible in most setups anyway

resources/grub/config/grub.cfg

@@ -155,23 +155,6 @@ menuentry 'Search ISOLINUX menu (AHCI)  [a]' --hotkey='a' {
 menuentry 'Search ISOLINUX menu (USB)  [u]' --hotkey='u' {
 	search_isolinux usb
 }
-menuentry 'Search ISOLINUX menu (CD/DVD)  [d]' --hotkey='d' {
-	insmod ata
-	unset ahcidev
-	unset atadev
-	if [ (ata?) != "(ata?)" ]; then
-		atadev=(ata?) # Only full drives not partitions
-	fi
-	if [ (ahci?) != "(ahci?)" ]; then
-		ahcidev=(ahci1) # TODO: hardcoded!!!
-	fi
-	echo -n "Attempting to parse isolinux menu from: "
-	for dev in ${atadev} ${ahcidev}; do
-		echo -n "${dev} "
-		try_isolinux_config "${dev}"
-	done
-	echo # Insert newline
-}
 menuentry 'Load test configuration (grubtest.cfg) inside of CBFS  [t]' --hotkey='t' {
 	set root='(cbfsdisk)'
 	if [ -f /grubtest.cfg ]; then