GitLab

Set shards to 3, as normal interactive_ui_tests does.

BUG=883523
TEST=none

Change-Id: Ia1fe3ec5e109b9d4b619c015525805e504e92d37
Reviewed-on: https://chromium-review.googlesource.com/c/1287197Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600591}