Add retries to run_suite create command

Retry on swarming internal error.

BUG=chromium:623206
TEST=None
Change-Id: I0d7cd300b963bb2a5df9f7b214a88ba59db01b20
Reviewed-on: https://chromium-review.googlesource.com/356212
Commit-Ready: Fang Deng <fdeng@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
2 files changed