Test case objects were sorted without key function, resulting
in random sort order. On sharded builds, the shards are
determined by the sort order and rely on a deterministic
sorting. This led to random cctest and unittest cases being
dropped or executed twice on sharded testers.

TBR=jkummerow@chromium.org, hablich@chromium.org

Review URL: https://codereview.chromium.org/1842673002

Cr-Commit-Position: refs/heads/master@{#35151}