Move GceMetadata into TastGceTest

This moves the whole message definition as well as the gce_metadata
field into TastGceTest message.
The messages have not been used yet so it should not cause any
problems.

BUG=b:187790569
TEST=./generate.sh --allow-breaking

Change-Id: I5911052b0e2a4618582ea352ada10b94d693b114
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/3353676
Reviewed-by: Shao-Chuan Lee <shaochuan@chromium.org>
Reviewed-by: Jaques Clapauch <jaquesc@google.com>
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Commit-Queue: Rintaro Kuroiwa <rkuroiwa@google.com>
3 files changed