Adding sync integration tests to official build artifacts

Following the steps done in https://codereview.chromium.org/323163003/

Not sure how to test this, any guidance?

I want the sync_integration_tests binary to be stored in
official Chrome build gs:// drops just like
browser_tests and other test binaries already are. Then
I can set up automation to approve new releases of Sync
server.

BUG=411389

Review URL: https://codereview.chromium.org/545103003

Cr-Commit-Position: refs/heads/master@{#293775}
3 files changed