Bluetooth: remove unnecessary state tracking in BluetoothSummaryUpdater

* LocalBluetoothAdapter is already a cache of BluetoothAdapter and its
  methods should be used directly to obtain states instead of caching them
  in BluetoothSummaryUpdater
    - Use LocalBluetoothAdapter.isEnabled() to check whether Bluetooth
      is enabled
    - Use LocalBluetoothAdapter.getBondedDevices() to get list of bonded
      devices
* BluetoothDevice is a stable Bluetooth API and its methods should not
  incur large latency. We should use API methods as much as possible to
  avoid intermediate wrappers
    - Use BluetoothDevice.isConnected() to check if a device is connected
* Add more logging messages in error conditions
* Show status as "Not Connected" when there is a state mismatch (i.e.
  adapter says it is connected, but no bonded device is connected)
* Updated unit tests to reflect the latest behavior

Bug: 65591907
Test: make, unit test, pair with Bluetooth devices, check Settings UI
Change-Id: I0fa54959c8bed8ac67a935f150785ba8197d0411