new_variant_fulltest: add depthcharge variant for guybrush

Guybrush supports a per-variant image for depthcharge, so enable
support in the test script and the new variant step list.

BUG=b:198303126
TEST=`testdata/new_variant_fulltest.sh guybrush && echo PASS`

Cq-Depend: chromium:3260768
Change-Id: I0731e3807645c3c96cd5f36eaaaae788fc775790
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/3258494
Tested-by: Paul Fagerburg <pfagerburg@chromium.org>
Reviewed-by: Raul E Rangel <rrangel@chromium.org>
Commit-Queue: Paul Fagerburg <pfagerburg@chromium.org>
2 files changed