Disconnect if the user cancels the no/partial connectivity dialog

If the user exits the no Internet or partial connectivity dialog
without taking any action, there is no longer any way to use the
network. So, disconnect the network.

Bug: 130766237
Test: clicking outside dialog disconnects network
Test: orientation changes do not disconnect network
Change-Id: I80c2c98c994dc01e53b32f40332b3f1bd03b6012