When Airplane mode is changed due to Voice Intent, use the system

provided ConnectionManager method to do that, instead of changing
it directly using Settings.Global.putInt() - because that doesn't
case ACTION_AIRPLANE_MODE_CHANGED intent to be broadcast.
This breaks Google Search App (GSA) code that relies on the above
broadcast to do a variety of things.

Change-Id: I2aa61643ed23b373aa362a59af83427a4548c492