Disable Keyboard Backlight on Thinkpad T440S at login

I accomplished the goal by putting

sudo sh -c 'echo 0 > /sys/class/leds/tpacpi\:\:kbd_backlight/brightness'

in a script.

I added this script to the sudoers file using the method in this answer:

How do I run specific sudo commands without a password?

I then added the script to System/Preferences/Personal/Startup Applications so that it runs at login. The user is not prompted for a password due to the script being in the sudoers file.

This has the desired effect of turning off the keyboard backlight when the user logins. It can be turned back on using the Fn+Spacebar key combination if desired.