build api metrics: propagate BUILD_API_METRICS_LOG down into pkg_size

sudo prevents environment variables from trickling down to subprocesses.
This fix allows BUILD_API_METRICS_LOG to flow down into the pkg_size
tool.

BUG=chromium:1000449
TEST=chromite/api/contrib/call_scripts/image__create ; validate that gauges are output correctly

Change-Id: I046b86c778a3e4ca0127c7d3248ae17c31c9c8e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/1853571
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Will Bradley <wbbradley@chromium.org>
Tested-by: Will Bradley <wbbradley@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
1 file changed