[le audio] Block newly connected device to become active when broadcasting

When the device is broadcasting audio, we need to block the newly
connected LEA and classic devices to automatically become active.
Instead UI will pop a dialog for user to select the next action.

Bug: 308171251
Bug: 308170200
Test: atest ActiveDeviceManagerTest AudioRoutingManagerTest
Test: manual test with classic & LEA BT devices
Change-Id: Ice378c71edf8f6cd5f02de4de0dc0489c8b41c64