Remove linux_angle_chromeos_rel_ng from default bots.
Remove linux_angle_chromeos_rel_ng from default bots.

This trybot was broken during the removal of the Linux ChromiumOS
Builder from chromium.gpu.fyi and is blocking all ANGLE CQ jobs.

BUG=762377
TBR=dpranke@chromium.org, jmadill@chromium.org
NOTRY=true

Change-Id: Ibc3ccf3af842ee8b040014732d179573f286afad
Reviewed-on: https://chromium-review.googlesource.com/653244
Commit-Queue: Kenneth Russell <1ebccd90c2bc76de65b6f830f2128a91ed69fdfb@chromium.org>
Reviewed-by: Kenneth Russell <1ebccd90c2bc76de65b6f830f2128a91ed69fdfb@chromium.org>

MSOpenTech/angle,ppy/angle,ppy/angle,MSOpenTech/angle,MSOpenTech/angle,ppy/angle,MSOpenTech/angle,ppy/angle