g3-mobly: Add par fetching from md from cros-test

We dynamically fetch the necessary pars to run mobly tests from the g3
bucket.

BUG=b:378499885
TEST=led

Change-Id: I03e2a6bb5f9c36734238772e14fdf6c70d9c2a21
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/6289183
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
Reviewed-by: Billy Zhao <billyzhao@chromium.org>
Commit-Queue: Billy Zhao <billyzhao@chromium.org>
Tested-by: Billy Zhao <billyzhao@chromium.org>
2 files changed