BuilderConfig: rename install_packages_conf.

BUG=chromium:1019868
TEST=generate.sh

Cq-Depend: chrome-internal:2498615
Change-Id: I544fcb618f8adbaba08bc7c38314488db355637a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2036238
Tested-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: LaMont Jones <lamontjones@chromium.org>
Reviewed-by: David Burger <dburger@chromium.org>
3 files changed