image_signing: drop "install" alias for factory

We migrated away from this in 2012, so drop the alias.  Any devices
made around that time won't need new factory images either.

BUG=None
TEST=None
BRANCH=None

Change-Id: I72a155d6c4c241781ec07b2ebb9a2393f8470a08
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1679436
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed