configs/chromebook_snow: remove defconfig, broken

This defconfig no longer builds:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/11012273111

It has been failing for over 2 months:

  https://gitlab.com/buildroot.org/buildroot/-/jobs?name=T%3Dchromebook_snow&kind=BUILD

It builds a 4.15 kernel, which is not even a maintained LTS kernel.

Unless a fix is provided, this defconfig will be removed.

Cc: Alex Suykov <alex.suykov@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>
(cherry picked from commit 9d1a7f5254)
Signed-off-by: Titouan Christophe <titouan.christophe@mind.be>

DEVELOPERS

@@ -99,8 +99,6 @@ F:	package/libzenoh-pico/
 F:	package/network-manager-openvpn/
 
 N:	Alex Suykov <alex.suykov@gmail.com>
-F:	board/chromebook/snow/
-F:	configs/chromebook_snow_defconfig
 F:	package/vboot-utils/
 
 N:	Alexander Clouter <alex+buildroot@digriz.org.uk>