Avoid using kStateDisconnect and kStateCarrier in NetworkState

NetworkState and NetworkStateHandler were generating
shill::kStateDisconnect for non-visible services and not connected
tether services.
However, shill::kStateDisconnect is a legacy status value from flimlam
and some chrome code doesn't expect this status to appear.
Use shill::kStateIdle instead.
Also avoid using kStateCarrier as it's not reported by shill anymore
either.

Bug: 552190, b:131667462, 954552
Test: Unit tests
Change-Id: I1ba28fba457682f45ae8816a7869f5c29f6fd200
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1591595
Commit-Queue: Pavol Marko <pmarko@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659741}
8 files changed