update cros_build_lib.run API usage

Switch to the new run API and away from the old RunCommand API.

BUG=chromium:1006587
TEST=CQ passes

Change-Id: I8897e4b3a90760457495845da3eb76cf9c3a3e6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/1965813
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
6 files changed