Where to change 30 seconds for grub on forced reset

When I start my Ubuntu there is this splash screen:

and i got rid of it by changing this line:

from
GRUB_TIMEOUT=2
to
GRUB_TIMEOUT=0

so it skips the grub right away.

But if I force reset/power off the machine I get this screen:

Now with 30 seconds countdown...

My question is where is this coming from, which file? I want to change it and it's not in /etc/default/grub

I found it on my own

in file /etc/grub.d/00_header

on line 333 there is a costant

set timeout=${GRUB_RECORDFAIL_TIMEOUT:-30}

and you can override it in /etc/default/grub file like this

GRUB_RECORDFAIL_TIMEOUT=0

and now even if i force reboot/power off it will skip the grub

lewis4u's answer works, but is more complicated than necessary.

Simply add the following line to /etc/default/grub:

GRUB_RECORDFAIL_TIMEOUT=5

I used 5 seconds, but you can use whatever value you want.