[crostestutils] Add a --fast flag to run_remote_tests.

This flag was added to test_that, and a similar copy can/should exist
for run_remote_tests.

TEST=ran run_remote_tests with --fast
BUG=chromium:258509

Change-Id: If566dd687373591bb36fd83c344e0817fd8a7748
Reviewed-on: https://gerrit.chromium.org/gerrit/61474
Reviewed-by: Alex Miller <milleral@chromium.org>
Tested-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
1 file changed