We cannot send PII data.

This CL tried to remove following data,
* build config that can contain build directory path
* build directory path
* hostname
* cwd

I use per build uuid instead of per user uuid.


Bug: 900161
Change-Id: Id533762749806ad8616b7dc07f21b27dfe632c9a
Reviewed-on: https://chromium-review.googlesource.com/c/1369473Reviewed-by: Shinya Kawanaka <shinyak@chromium.org>
Reviewed-by: Fumitoshi Ukai <ukai@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>