volteer2.py: use add_fitimage.sh instead of add_fitimage_qs.sh

Remove unused volteer.py.

BUG=b:189405521
TEST=none

Cq-Depend: chrome-internal:3917503
Change-Id: I3eb3a8361b226bfb6ad4af3dd76176dedef093b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2976864
Tested-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Zhuohao Lee <zhuohao@chromium.org>
Commit-Queue: Nick Vaccaro <nvaccaro@google.com>