cellular: Disable autoconnect during test environment setup

BUG=chromium:403164
TEST=network_3GSmokeTest

Change-Id: I8f4f765045b74d690afb7af5fa75b249372b4407
Reviewed-on: https://chromium-review.googlesource.com/218446
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Thieu Le <thieule@chromium.org>
Tested-by: Thieu Le <thieule@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
2 files changed