Merge changes from topic 'exponential backoff periodic scan' into nyc-dev

* changes:
  WifiConfigManager: clean up makeChannelList()
  WifiStateMachine: clean up dead code
  WifiConnectivityManagerTest: exponential backoff periodic scan
  Restrict connectivty periodic scan
tree: 9ea1a17b8bebce4cce0b361633d083c89e6b3197
  1. service/