[LE Audio] To fix the condition of the broadcast icon display

 - The broadcast icon will be displayed when the device is connected to
   the LE Audio device.

 - The broadcast option dialog will show the "Broadcast" option when the
   media is streaming. Otherwise, it will not show.

Bug: 235923182
Test: manual test
Test: make RunSettingsRoboTests ROBOTEST_FILTER=MediaVolumePreferenceControllerTest
Change-Id: Ib225d185b6f15463f4fae809e0cdaa25920d52af