Disable roaming sanity checking.

We've traced down all code paths where NetworkInfo.isRoaming() and
NET_CAPABILITY_NOT_ROAMING can disagree, so we're only left with
noise that happens from NetworkAgent race conditions when someone
asks for a NetworkState between pending NetworkInfo and
NetworkCapabilities updates.

We can look at adding a way for a NetworkAgent to update these
two objects atomically, but not for this release.

Bug: 70174865
Test: builds, boots
Change-Id: I830e1fc6dc922e9eb7f8c2698d75181e00aaf7fb