Broadcast Adapter state change in a Flow

No longer randomly wait for 10x 300 ms but instead use a wrapper on the
state to make sure no intermediate event are missed

Bug: 262605980
Test: atest ServiceBluetoothTests
Test: adb shell cmd bluetooth_manager disable && \
      adb shell cmd bluetooth_manager wait-for-state:STATE_OFF
Change-Id: Ie0f954dd2b4afb3db612f503eaf4771ef9a5ec2b